Protect your regulator from water, dirt, dust and crawling critters. Keeping your regulator protected from the elements when it is not connected to a cylinder is important to your safety and the reliability of your Life Support System. This non-corrosive Delrin Plastic DIN Protector Cap is the best kind to ensure proper protection. It threads in place to protect your regulator from having water enter inside the delicate internal mechanism when washing your gear after diving. Precision machined from anodized aluminum. Protects threads on DIN first stage. Seals water out of first stage. Attached nylon cord lanyard.