Captain O-RingReplacement Seal Oring for SunSun HW304A, HW304B Canister Filter (2 Pack)

Okay, so I'm am not 100% that the O-ring was the issue, but I had the filter for 7?ish years, and then the filter was dissembled for a couple months were it was just sitting open to air.I bought this new set, and installed it with some petroleum jelly. I do think that my leak was from the UV light cover not being fully inserted and locked in the filter head, BUT I am still glad I replaced the O-ring for my piece of mind.The price is very reasonable and you get two of them. If you even suspect that it is the o-ring, or your filter has been running for years without a change, go ahead and buy these. It can't hurt and now you also have a spare.Or just buy them now so if you do have a leak they are on hand.I keep my filter in one of those big bucket tubs that they sell for keeping toys and sports equipment in. I also have a water sensor that screams if it gets wet. I set the senor in the bottom of the tub, and the box with the battery to the side. It has definitely saved me when some leak occurs and the thing goes off at 5 in the morning screaming, with the tub catching everything and saving my floors.

THANK YOU!!! I've had to toss 2 filters because I couldn't find a new oring to fit them and been searching for years! Had an issue with it not sealing over the weekend and tried all the usual tricks to no avail. Forgot I had bought these a couple months ago until they literally fell off the shelf into my lap lol. Replaced it and worked immediately!!!

I was concerned this would not fit my 304B sunshine filter as it was listed as a 704B part. I had nothing to worry about, after greasing, it was installed easily, and I have had no leaks in the two weeks my filter has been running. I now have extra on hand and a better part replacement schedule.

Work great

Fits like a glove fixed my issueThanks for a great product and a decent price

as per describe dimension, good quality.

These are the wrong size (thickness) for the HW-304B, and will leak whenever the filter loses power / is turned off after a few days.

Purchased these to replace in my filter that wouldn't stop leaking. I also got Vaseline as per some recommendations. Worked like a charm and no more leaks!If you keep opening your filter, you will need to buy these. Only open it during the quarterly cleanings!