Cressi original replacement of the lower snorkel purge valve. The valve gives the possibility to blow out any water that may have entered the tube. The valve is compatible with only these Cressi models: Mini Dry. The valve has a pin that has to be inserted in the hole of the lower part of the snorkel. Made of silicone. Cressi has been an Italian brand pioneer in scuba diving, freediving, and snorkeling equipment since 1946.