The PAS Sleeveless Base Layer is constructed to disappear. This piece is based on our Mechanism Pro Sleeveless Base Layer. Made from a unique knitted fabric, the base layer allows heat and moisture to escape from your skin, actively cooling you down when moving. The PAS Sleeveless Base Layer is made to work as part of our pro-level system of performance kit, leveraging the output of your efforts on the hardest days on the bike.