Culligan OR-34 O-Ring of 4.125-Inch Diameter Inlet/outlet filter housing O-ring For use with Culligan Filter Sediment Water Filters HF-150, HF-160, and HF-360 For residential use The OR-34 rubber o-ring gasket is 4.125" in diameter and is a Buna-N o-ring. The OR-34 o-ring gasket is used to seal the housing bottom to the housing top to prevent leaks. The OR-34 o-ring gasket should be lubricated with silicone lubricant to prevent leaks in the water filtration system. The OR-34 can be used Ace Hardware, American Plumber, Ametek, Culligan, MasterPlumber, Pentek, and US Filter Plymouth Products. The OR-34 oring should be replaced every two filter changes or if there is damage to the OR-34 oring.