I tested the Seal Skinz socks by wearning them and dipping them under water. The pair is 18 months old. One of the socks failed the water-proof test. A little bit of water sipped in through the material to my skin. That renders the socks invalid for wudu making purposes. If you have Seal Skinz socks you should also test them for water-proofability from time to time. Comments appreciated.