THICKNESS - The body is designed using 3mm Syprene neoprene on the front and back for buoyancy and thermal insulation. While the 2mm neoprene on the underarms and crotch panels offer maximum flexibility when swimming and running.MATERIALS - The front is constructed using Syprene neoprene which has a tough surface treatment that protects the suit surface from minor abrasions caused by rocks, sand or gravel during transitions. The back, underarms and crotch panels are made out of extra-stretch double-sided nylon for flexibility and water speed.CLOSURE - Long front single-zip to help get the suit on and off. You can also leave the upper part of the zipper open during the run to improve cooling and ventilation. Comes with an emergency whistle built into the zipper pull.STORAGE - This suit has a lot of pockets so you have room to store everything you need. It has two large inner chest pockets where you can store your emergency kit, map and nutrition and one large back pocket with a zipper.LINING - This inner lining is smooth and comfortable against your skin and helps store body heat. ADDITIONAL SIZING GUIDANCE: Use your weight to determine your size. If you have longer legs and a shorter torso, subtract 2” from your height. If you have shorter legs and a longer torso, add 2” to your height. If you have a larger chest and/or shoulders, add 7 lbs to your weight. If your measurements are between two sizes, we recommend a larger size wetsuit if you have broader shoulders, a larger chest or disproportionately bigger/stronger upper or lower body. Choose a smaller wetsuit if you prefer a race fit and are comfortable with a snug fitting wetsuit or you anticipate shedding weight from physical conditioning.