Rule Shower Drain SumpA full capacity shower drain system with automatic activation. Includes a clear, screw down cover for easy inspection, removable strainer for easy cleaning, and an internal check valve to prevent back siphoning. Consists of a Rule bilge pump, Rule A Matic float switch and an enclosing sump. This unit includes one 1. 5 inch inlet (not 3 as shown in the picture) and one 3 4 inch outlet.