The Trap Tite Trap Seal is designed to be used in conjunction with a code approved trap seal (often referred to as a P-trap) in drainage systems including floor drains. Trap Tite is available in 4 sizes: 2, 3, 3.5 and 4. Typical applications for the Trap-Tite include 2, 3, and 4 floor drains, basement drains, mop sink drains, and other types of drains used in maintenance areas. The Trap-Tite blocks harmful sewer gases and/or pests from entering a finished building space in the event that the P-trap is not sealed with an appropriate amount of liquid.