O’Neill’s Psycho Tech mens 5.5/4 wetsuit combines exclusive TechnoButter 3 neoprene with TechnoButter 3 Air Firewall insulation, Stitchless Seam technology with exterior Single Fluid Seam Weld, internal TB3X Tape and a Z.E.N. zip Closure Sytem. Lighter, warmer, more insulating and quick drying with improved ease of entry. PsychoTech is the latest advancement in cold water wetsuit technology from the leaders in innovation for over 60 years. Technobutter 3 neoprene O'Neill's exclusive new pre-stretched neoprene with featherlight, ENVY foam rubber core. Ultimate, flexibility, warmth and comfort. Built to last. Patented Z.E.N. Zip entry with drainhole O’Neill’s innovative patented Z.E.N. Zip Entry system is the most imitated entry/closure system in the world. This free floating exterior mini zip allows for a zipperless feel and stops water from entering the wetsuit. (U.S. Patent #5,898,934). Pullover internal seal that blocks out water for maximum performance. Water that penetrates the Z.E.N. Collar or Super short zip is blocked by the Barrier-2 and forced out the drain hole. Double superseal neck A toasty warm two layer design featuring a 360˚ smooth skin interior lining, wide adjustablility, and a secure lock down. Fully adjustable and watertight. Strategic seamless paddle zones An ergonomic, seamless under sleeve panel that allows for unrestricted motion and eliminates rashing. Flexible and unique design which utilizes minimal seam placement for comfort.