MTM replacement O-Rings allow you to fix issues you have with your pressure washing fittings.
If you have a leaking coupler of your sprayer or wand, you probably have a missing or damaged O-Ring. You'll want to have a few of these on hand for when that eventually happens as these are wear items.
Dont get caught without a few extra O-Rings on the job as these little items make a big difference in maintaining PSI, GPM, and safety.