Test Good neoprene should resist squeezing, and snap back into shape when released after being pinched. The better the neoprene stretches, the better it will conform to your shape. Maximum stretch should be around the diameter of arms, legs and torso, but not down their lengths. Skin-sided neoprene refers, of course, to naked neoprene unlined with nylon. Nylon will wick water, but smooth neoprene makes a pretty good seal against your skin or itself.
Naked neoprene makes the best seal but deteriorates after a while.
It slips on more easily, but may not seal quite as well. Given a well-fitting suit, these seals do a pretty good job of keeping the water out. My arms got damp, but not enough water entered to circulate. My torso and my legs stayed dry. More important, the hood is attached to the suit and the face opening is sealed with a two-inch band of Glideskin, so water entry down the neck is practically eliminated.