1. [1 5/8' Sink Drain & 1 1/4' Bottle Trap]Compatible with sinks with 1-5/8' (Φ41mm) drain opening and overflow hole, not with sink drain holes that are smaller than 1 5/8', such as those measuring 1 1/4' or 1 1/2'. Bottle trap has a standard 1-1/4' waste outlet pipe for easy installation 2. [Multiple Anti-leakage Design]The enhanced thickened silicone gaskets included, fit the drain better and are anti-oxidation. With the 3-piece sealing ring design to prevent water leakage more effectively 3. [No Sewer Gases]The waste water flows into the round bottle trap that forms a water seal, blocking the sewer gases from entering your home. When you use the faucet, fresh water replaces the old water in the trap, keeping it clean automatically 4. [Removable Cleanout Cover]The trap has a Trap Eye at the bottom that you can unscrew to remove any debris or clogs. Simply place a bucket under the sink, open the cap, and let the waste fall out