MARES AST 1ST STAGE DRY SYSTEM – DIN, Regulator First StageMares AST 1st Stage Dry System DIN Automatic Sealing and Regulator Protection The Mares AST 1st Stage Dry System DIN offers advanced protection for your regulator by keeping the first stage completely dry when not connected. Featuring Mares innovative Auto Sealing Technology (AST), this system automatically closes the first stage inlet, preventing dust, water, and debris from entering ideal for both cold water and tropical diving environments. AST