KPOST Drain Backflow Preventer, One Way Seal Tight Drain for Sink and Tub, Resist Odor

I had to sand down the outside flange to fit my application, as it is designed to fit a variety of pipe sizes - so this was expected. A little bit of sanding and it fit perfectly. It takes just a small amount of water inside the unit and it trips the spring pressure and the valve opens. There is zero standing water in the shower - none at all. Unlike other backflow preventer valves, this one drains all the water all the time as it is very sensitive and does not need to have standing water in the shower pan to trip the diaphragm valve. I would buy this product again and would recommend this product to others.

I bought this hoping it would just slide in. It didn't so I went to local hardware store and bought two rubber seals. Slid in place and has worked great and has stopped all smells from come from the septic. Great product and saved me lots of work. Well worth the money. Seller was very helpful.

it's cheaply made and hard to get a seal, so it leaks and when tightened just a little to get plumber's putty to work, it broke.

Excellent product. Water flows good through this. I use it On my SHI we drain. You may have a very small flow issue if you use too much soap but nothing major. Had to use the adapter to fit my 2” pipe opening. It states it will fit 2” pipe but it is slight under 2” so you must use the adapter ring which can be easily be cut down to size using scissors.

Overall quality is a 5/5 I'm using it in a zero entry shower and haven't had a run over. I'm super happy with it. The only annoying thing is that the flange is about 1/16" too large for a standard round US floor drain. No big deal, a little sandpaper around the edges and this will fit perfectly.

Was to small and not enough give to fit

I used this on a shower where I didnt have enough room for a p-trap. This lets the water flow and keeps in the gases out.

It broke immediately