Good quality and preforms great
These should be put on every air line you have in every aquarium. I find these to be of better quality than others I've tried.
Not much you can say about a check valve. Shipping prompt, well packed. The valve has been in use since it arrived, and appears to be functioning as it should.
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.