The Prolimit Mercury TR V-back zip steamer wetsuit for men is our best-selling suit. The suit has Thermal Rebound (TR) technology, this is an extra layer in between the neoprene and zodiac that reflects body heat and blocks wind chill. Besides the tr, the neoprene of the suit is 6mm thick, which makes it one of the warmest wetsuits on the market. Compared to the Mercury TR free zip and the Mercury TR free x, this suit has a zipper on the back with a leash.