Watts 1-1/2" PVC S-Trap Complete. This 1-1/2" Plastic S-Trap with Plastic Threaded Adapters designed for use in tubular drain applications such as sinks. S-Traps are the most commonly used in houses and commercial sinks. The S bend is designed to not jam, but still needs an overflow. S-Trap wont let unwanted gases into the building. Available in white polypropylene plastic.