Those on that pic could be Neoprene but I somewhat doubt they're waterproof, you can clearly see stitching holes and those will allow water to get in. It should at least be blindstitched and to be totally waterproof, on top of that also sealed with liquid rubber.
GoreTex is a textile structure that blocks liquid water but lets damp pass.
But when too small the same applies as all the others: bloodtransport is slowed and cold.
It's expensive.