Factor 1 Plus Mens Sleeveless Base Layer Top

Factor 1 Plus Mens Sleeveless Base Layer Tops are ideal for adventurers who need to add extra bodily core insulation without bulking out the arms. 

Manufactured from super soft 100% polyamide fabric, these base layer tops utilise body mapping technology to construct innovative seamless body forms, enabling features such as stretch rib zones for support and waffle zones for enhanced heat retention and greater perspiration control. 

Knitted in one piece, the only seams present are on the shoulders, and these are closed using a flat seam to prevent rubbing. The round neck has been designed so that it stretches when placed over your head and its low profile also means it is not prominent when worn under clothing. Body lengths in all our base layer and mid layer designs are long,  giving the wearer a decent amount of fabric to tuck in to their trousers or shorts. This helps to avoid lower back exposure during activities and when sitting down.

These Sub Zero tops are one of the best lightweight thermal underwear ranges for general outdoor use. The simple design makes them compatible with most sports where you need to keep warm and dry. They cross over in to anything from skiing  through to hiking and camping, and can be used in combination with the Sub Zero Factor 2 thermal mid layer range for extra warmth in extreme conditions.

Scroll down the page for further product details, technical information, sizing, shipping and any washing instructions.

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$45

Only 24 left in stock.
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  • Body mapping technology
  • Long body length
  • Low profile armholes
  • Low profile crew neck finish
  • Lots of stretch both vertically and horizontally
  • Easy to wash, quick to dry
  • Super soft polyamide fabric
  • Made in: Great Britain
  • Brand: Sub Zero
  • TOG: 0.47
  • Fabric: 100% Polyamide
  • Average weight: 140g / 4.9oz (exact size weights found in the Size Chart section)
  • Fit: Snug
  • Layer: First - next to the skin
  • Size availability: Medium-XLarge
  • Colour: Black
  • Fabric treatments: Hydrophilic wicking management

SIZING GUIDE
There are no standard sizes for clothing, which is why each brand has their own unique cut and fit. Please do not presume you are the same size between brands for a similar product. If you have a base layer that fits correctly, then use it as a template for these measurements.  

HOW TO MEASURE
Chest - Measure the full circumference of your chest just below the armpits
Waist - Measure the full circumference at the top of your hips
Back Drop - Measure from the back of your neck to the base of your spine
Arm Length* - Measure from the end of your shoulder to your wrist

* This measurement is only applicable for long sleeves. Short sleeve versions of the base layer tops finish just above the elbow. 

BASE LAYER FIT
Our base layers have a lot of stretch, so they will contour to most body shapes when worn. You should wear them close fitting but not so they are restrictive. Wearing baggy or ill fitting base layers will lead to the loss of heat and a reduction in their wicking properties.

Please be aware that these measurements are taken from the garments unstretched, apart from the 'TO FIT CHEST' column, that indicates the range of fit. The back-drop is the critical measurement. This ensures the body length is correct to prevent lower back exposure. Even if the chest measurement looks too small, the stretch of the fabric will enable a good fit.   

The table below shows the garment measurements for our Factor 1 Plus base layers. There is a tolerance of +/- 5mm.

SIZE CHEST TO FIT CHEST WAIST BACK DROP ARM LENGTH
cm in cm in cm in cm in cm in
XSMALL 71 28 71-79 28-31 79 31 63 24 61 24
SMALL 74 29.5 81-87 32-34 80 31.5 65 25 62 24.5
MEDIUM 79 31 89-94 35-37 85 33.5 67 26 63 25
LARGE 85 33.5 97-102 38-40 91 36 69 27 64 25.5
XLARGE 91 36 104-107 41-42 97 38 71 28 65 26
XXLARGE 92 36.5 109-114 43-45 98 38.5 74 29 68 27

 

The table below shows the actual garment weights per size for each of the different styles of Factor 1 Plus base layer tops we manufacture. There is a tolerance of +/- 10g. 

SIZE LONG SLEEVE SHORT SLEEVE ZIP LONG SLEEVE ZIP SHORT SLEEVE VEST
g oz g oz g oz g oz g oz
XSMALL 160 5.6 130 4.6 - - - - - -
SMALL 175 6.2 140 4.9 185 6.5 155 5.5 - -
MEDIUM 190 6.7 160 5.6 200 7.1 175 6.2 120 4.2
LARGE 210 7.4 175 6.2 220 7.8 190 6.7 135 4.8
XLARGE 230 8.1 185 6.4 240 8.5 210 7.4 150 5.3
XXLARGE 240 8.5 205 7.2 - - - - - -

 

 

We ship worldwide using Royal Mail & UPS. All UK orders over £35 are shipped free of charge.

For more information regarding our shipping, including charges and estimated delivery times, please visit our Shipping Page

If you are unhappy with your purchase, please return it to us within 180 days of receipt. To be eligible for a return, your item must be in the same condition that you received it, unworn or unused, with tags, and in its original packaging.

For more information regarding our returns policy please visit our Returns Page

Washing instructions for Sub Zero base layers are printed on a white silk tag stitched to the back neck and can also be found knitted in to the waist band. Please follow these instructions carefully as failure to comply with them will make your guarantee void. If you have removed the tag or are unsure of the washing symbol meaning, the full washing instructions can be found below.

  • Machine wash or hand wash in water not exceeding 40°C or 105°F
  • You can use a mild washing detergent but ideally you want to use a base layer specific washing treatment 
  • Wash dark colours separately, do not bleach, do not use fabric conditioners
  • These base layers can be spun dry in a washing machine
  • Do not tumble dry. These base layers will quickly dry on a line or airer as they retain very little water once spun/rung out. 
  • Do not dry clean
  • Regular ironing may be performed at a low setting (110°C, 230°F) only, but we advise against it.

 

GENERAL WASHING TIPS
When you go to wash any garment with a zip, ensure it is done up fully otherwise the exposed teeth may cause harm in the wash cycle. The same can be said for garments containing Velcro. Your best course of action would be to wash these garments either by hand or on their own in a washing machine.

With the advancement in detergent technology, you very rarely need to wash any garments these days above 30°C. It is better to use a specific anti-bacterial wash-in treatment rather than increasing the temperature.

A lot of Sub zero products, especially the base layers and mid layers, can be ironed on a low temperature setting. We would advise against this as the heat settings on irons are not always reliable. In any case, the stretch properties of synthetics helps reduce creases in the wash and if there are any afterwards, they often drop out when worn.

Like most synthetics, Sub Zero fabrics will melt or burn if exposed to flame or direct heat. They are not flame resistant; do not use them near ANY direct source of heat or flame. This includes some of our merino wool products that contain a small percentage of synthetic yarn.

  • Body mapping technology
  • Long body length
  • Low profile armholes
  • Low profile crew neck finish
  • Lots of stretch both vertically and horizontally
  • Easy to wash, quick to dry
  • Super soft polyamide fabric
  • Made in: Great Britain
  • Brand: Sub Zero
  • TOG: 0.47
  • Fabric: 100% Polyamide
  • Average weight: 140g / 4.9oz (exact size weights found in the Size Chart section)
  • Fit: Snug
  • Layer: First - next to the skin
  • Size availability: Medium-XLarge
  • Colour: Black
  • Fabric treatments: Hydrophilic wicking management

SIZING GUIDE
There are no standard sizes for clothing, which is why each brand has their own unique cut and fit. Please do not presume you are the same size between brands for a similar product. If you have a base layer that fits correctly, then use it as a template for these measurements.  

HOW TO MEASURE
Chest - Measure the full circumference of your chest just below the armpits
Waist - Measure the full circumference at the top of your hips
Back Drop - Measure from the back of your neck to the base of your spine
Arm Length* - Measure from the end of your shoulder to your wrist

* This measurement is only applicable for long sleeves. Short sleeve versions of the base layer tops finish just above the elbow. 

BASE LAYER FIT
Our base layers have a lot of stretch, so they will contour to most body shapes when worn. You should wear them close fitting but not so they are restrictive. Wearing baggy or ill fitting base layers will lead to the loss of heat and a reduction in their wicking properties.

Please be aware that these measurements are taken from the garments unstretched, apart from the 'TO FIT CHEST' column, that indicates the range of fit. The back-drop is the critical measurement. This ensures the body length is correct to prevent lower back exposure. Even if the chest measurement looks too small, the stretch of the fabric will enable a good fit.   

The table below shows the garment measurements for our Factor 1 Plus base layers. There is a tolerance of +/- 5mm.

SIZE CHEST TO FIT CHEST WAIST BACK DROP ARM LENGTH
cm in cm in cm in cm in cm in
XSMALL 71 28 71-79 28-31 79 31 63 24 61 24
SMALL 74 29.5 81-87 32-34 80 31.5 65 25 62 24.5
MEDIUM 79 31 89-94 35-37 85 33.5 67 26 63 25
LARGE 85 33.5 97-102 38-40 91 36 69 27 64 25.5
XLARGE 91 36 104-107 41-42 97 38 71 28 65 26
XXLARGE 92 36.5 109-114 43-45 98 38.5 74 29 68 27

 

The table below shows the actual garment weights per size for each of the different styles of Factor 1 Plus base layer tops we manufacture. There is a tolerance of +/- 10g. 

SIZE LONG SLEEVE SHORT SLEEVE ZIP LONG SLEEVE ZIP SHORT SLEEVE VEST
g oz g oz g oz g oz g oz
XSMALL 160 5.6 130 4.6 - - - - - -
SMALL 175 6.2 140 4.9 185 6.5 155 5.5 - -
MEDIUM 190 6.7 160 5.6 200 7.1 175 6.2 120 4.2
LARGE 210 7.4 175 6.2 220 7.8 190 6.7 135 4.8
XLARGE 230 8.1 185 6.4 240 8.5 210 7.4 150 5.3
XXLARGE 240 8.5 205 7.2 - - - - - -

 

 

We ship worldwide using Royal Mail & UPS. All UK orders over £35 are shipped free of charge.

For more information regarding our shipping, including charges and estimated delivery times, please visit our Shipping Page

If you are unhappy with your purchase, please return it to us within 180 days of receipt. To be eligible for a return, your item must be in the same condition that you received it, unworn or unused, with tags, and in its original packaging.

For more information regarding our returns policy please visit our Returns Page

Washing instructions for Sub Zero base layers are printed on a white silk tag stitched to the back neck and can also be found knitted in to the waist band. Please follow these instructions carefully as failure to comply with them will make your guarantee void. If you have removed the tag or are unsure of the washing symbol meaning, the full washing instructions can be found below.

  • Machine wash or hand wash in water not exceeding 40°C or 105°F
  • You can use a mild washing detergent but ideally you want to use a base layer specific washing treatment 
  • Wash dark colours separately, do not bleach, do not use fabric conditioners
  • These base layers can be spun dry in a washing machine
  • Do not tumble dry. These base layers will quickly dry on a line or airer as they retain very little water once spun/rung out. 
  • Do not dry clean
  • Regular ironing may be performed at a low setting (110°C, 230°F) only, but we advise against it.

 

GENERAL WASHING TIPS
When you go to wash any garment with a zip, ensure it is done up fully otherwise the exposed teeth may cause harm in the wash cycle. The same can be said for garments containing Velcro. Your best course of action would be to wash these garments either by hand or on their own in a washing machine.

With the advancement in detergent technology, you very rarely need to wash any garments these days above 30°C. It is better to use a specific anti-bacterial wash-in treatment rather than increasing the temperature.

A lot of Sub zero products, especially the base layers and mid layers, can be ironed on a low temperature setting. We would advise against this as the heat settings on irons are not always reliable. In any case, the stretch properties of synthetics helps reduce creases in the wash and if there are any afterwards, they often drop out when worn.

Like most synthetics, Sub Zero fabrics will melt or burn if exposed to flame or direct heat. They are not flame resistant; do not use them near ANY direct source of heat or flame. This includes some of our merino wool products that contain a small percentage of synthetic yarn.

Customer Reviews

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Factor 1 Plus Mens Sleeveless Base Layer Tops are ideal for adventurers who need to add extra bodily core insulation without bulking out the arms. 

Manufactured from super soft 100% polyamide fabric, these base layer tops utilise body mapping technology to construct innovative seamless body forms, enabling features such as stretch rib zones for support and waffle zones for enhanced heat retention and greater perspiration control. 

Knitted in one piece, the only seams present are on the shoulders, and these are closed using a flat seam to prevent rubbing. The round neck has been designed so that it stretches when placed over your head and its low profile also means it is not prominent when worn under clothing. Body lengths in all our base layer and mid layer designs are long,  giving the wearer a decent amount of fabric to tuck in to their trousers or shorts. This helps to avoid lower back exposure during activities and when sitting down.

These Sub Zero tops are one of the best lightweight thermal underwear ranges for general outdoor use. The simple design makes them compatible with most sports where you need to keep warm and dry. They cross over in to anything from skiing  through to hiking and camping, and can be used in combination with the Sub Zero Factor 2 thermal mid layer range for extra warmth in extreme conditions.

Scroll down the page for further product details, technical information, sizing, shipping and any washing instructions.