Work great thanks
If you're new to sponge filters like me, check valves are a must-have! They prevent the water from siphoning out of the tank and back to the air pump if the power shuts off. I had to check a few YouTube videos, but if the red part of the valve looks like a top hat, then the brim/bottom of the top hat should be facing/closer to the air pump and the top of the hat should be facing/closer to the sponge filter. The product itself looks to be of good quality and pretty robust. Definitely worth the add-on.
........ and it works!
As other reviewers have noted, this check valve is of better construction than others on the market. I will be ordering more to have a few extra on hand.
Fast delivery and low price, I had a power outage the other day and this worked just fine. Would recommend