Check the listing for details. Culligan OR-34 Replacement O-Ring use with HF-150 HF-160 HF-360 2-Pack. Color: Black, Condition: New. Listed at 5.95 USD. CULLIGAN REPLACEMENT O-RING For use with HF-150, HF-160 & HF-360 units The Culligan OR-34A O-ring 2-pack includes O-rings labeled A and B. If you are looking for the O-ring from the old OR-34 single O-ring pack you need the O-ring tagged with a B, which fits housings that use a 4 1/8-inch outside diameter O-ring. The O-ring tagged with an A fits housing that use a 4-inch outside diameter O-ring. Over time the O-ring that comes with your filter housing will wear down and may leak so you should replace your O-ring after every 3rd filter change. Replace your O-Ring with every 3rd filter change to prevent leaks.The OR-34A replaces the OR-34 and now contains 2 O-rings - 4 1/8 inch outside diameter O-ring (previously called OR-34) and 4 inch outside diameter O-ring