Factor 1 Plus Mens Sleeveless Base Layer Vest 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 vest 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 vest 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 range for extra warmth in extreme conditions.

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