Amazon.com: APEC Water Systems SET 3 Pcs 3.5" O.D. Replacement O-Ring For Reverse Osmosis Water Filter Housings, 3 Count (Pack of 1), Black : Tools & Home Improvement
APEC Water Systems 3.5 in. O.D. O-Ring Set (3-Pack) for 10 in. Standard Reverse Osmosis Filter Housings O-RING-SET - The Home Depot
RO Membrane housing replacement O-Rings – Desert Water Conditioning