Description: Part # 075037 is a universal 3/8" O-ring designed to fit most quick connect couplers. The O-ring ensures a tight seal around coupled quick-connect joints through which water passes like hoses, nozzles, and wands. While they are made of durable Buna rubber, they should be replaced over time. It's a good idea to keep several O-rings on hand in your on-site pressure washing supplies, or on your trailer-mounted pressure washing rig. Material: Buna. Size: 3/8".