Mesh single lined Neoprene
Mesh is the term for neoprene without the usual external nylon coating. It is very flexible and thus more comfortable than nylon coated neoprene and also warmer in strong winds.
Single lined should only be used in carefully chosen areas of the suit as it is more prone to damage from sharp objects.  

Super Stretch
Also known as "X" Stretch or Double Superstretch Neoprene. Developed for excellent stretch and memory. Hardwearing stretch nylon on the outside with softer super stretch nylon on the inside provides excellent comfort and fit.