0.3 mm neoprene, super thin, great temperature regulation. Excellent condition, I've worn this top maybe 10 times and have always taken great care (cold water rinses and almost zero exposure to UV) Most of the times I have worn this, the outer layer would be shedding water and I would still dry on the inside.

Wear it on its own or wear it as a baselayer when you know that conditions are going to get wet.

Note: This is the full neoprene version (not the hybrid ZSkin version which only has neoprene at the core and back and instead uses spandex mesh panels for arms.)