Sydien Silicone Seal Resist Smell and Bugs Drain Backflow Preventer for Pipes Tubes

Extremely useful and it saved me from getting busted.

Shows two but you'll receive one

It avoids odor get out of the pipe while also allowing the water to easily drain. Installation was very simple. Good product

The new clothes washer has higher discharge rate and would overwhelm the old 1 1/2" ID drain pipes and cause backup through the floor drain in laundry room (about a gallon each rinse cycle). Bought the 34-39 mm version and installed in the drain. The fit was not very tight so I added a bead of sealant/glue under the lip of the Silicone part and another inside the rims of the metal insert and grate that comes with it.Ran the washer and when it discharged the surge in water pushed the lower part of the blue Silicone inside the upper part and was stopped from going any further by the grate, where it remains. That being said, only about a cup of water leaked through and it drained out right away when the washer quit discharging. Ran a couple of more wash loads with the same results. So, I'm satisfied; I can live with the cup of water. Hope it lasts!(Note: The first time I ran the washer I didn't have the little metal grate on and the lower part pushed completely through the upper part and shot a stream of water all over the place. Maybe making the lower part a bit stiffer would prevent this reversal? )