Your DIN first stage threads are the one part of your regulator you really do not want to bang around in a gear bag. This plastic cap from Dive Rite slips over the DIN fitting and keeps the threads from getting damaged, dirty or wet while your regs are in transit between dives. It is a cheap bit of insurance for an expensive piece of life support. Caps have a way of walking off, so you can never keep too many on hand.
