Captain O-RingOK7 Replacement O-Ring Kit for OmniFilter BF6, BF7, BF7a, BF35, BF36, BF36C, BF55, BF56, PB35, PB55 (2 Sets - 4 Total Orings, 2 Sizes)

I have an older BF7 whole house filter and when I replaced the O-Ring with a standard replacement I could not get it to stop leaking. I put the old O-Ring back on and ordered the Captain O-Ring-OK7 replacement set that included the oversize O-Ring along with the OEM size. It worked great. Don't know how they found out this was a common problem with this unit and started including the extra size option but I am glad they did.

The device work as I expected it to

I measured the O ring from a new BF7 unit and the original ring with the unit was bigger than the small ring in the package and the 2nd size in the package was larger than the original ring. I suspect that the oversize ring would work if you ran into a leakage issue. I am keeping these just in case I have a problem in the future. Reasonable price and if functional. Seems like the best choice as none of the seller show the size of the O rings being sold.

Wrong size o-ring needed to be 5 and 5/8 was 5 and 3/4