Veloci Performance O-Rings will fit in any 1/4", 3/8", and 1/2" coupler in the U.S. Market. Veloci sells well over 100,000 o-rings per year because they are commonly lost at the worst of times. From amateurs to contract cleaners, everybody blows out o-rings, the difference is the pro's always have a few spare o-rings on hand.
 
Don’t get caught without a few extra o-rings on the job. A small investment makes a big difference in maintaining PSI, GPM, and safety.
 
Note: price is for 1  O-Ring