P Trap Pal manufactures and sells check valves to prevent sink odor in your kitchen and bathrooms. When faucets are not run on a regular basis, the p-trap under the sink can dry out and allow sewer odor and insects into your home. P Trap Pal has a patented check valve design that prevents sewer odor and insects from entering your home. These valves are easily installed by hand inside the p-trap under your sink.