Captain O-Ring - Culligan OR-34A (2 pack) Replacement O-Rings for Culligan and Ace Filters (2 Sets, 4 O-Rings) Includes 4 O-Rings (2x Smaller "A" O-Ring and 2x Larger "B" O-Ring) Fits: Culligan HF-150(A), HF-160, HF-360(A), and others (see description below) OR-34A should be replaced every two filter changes, or when leaking. Compatible with silicone lubricant (and many other lubricants) to ease installation. Manufactured and Warrantied by Captain O-Ring LLC