The Thermo X is 13oz of pure performance and comfort. With its water repellency and odour resistance properties this top will keep your core toastie. The 4 way stretch fabric, rash protection, strategic seamless paddle zones and low crew neck (no interference with wetsuit neck) means the only thing you need to concentrate on is nailing that one manoeuvre!!! (also great as an under garment for any sports where you need another layer, running, mtb, etc)