The Waterway 400-4200 is a Union Tee designed for plumbing connections, featuring a 1.5" Female Buttress Thread (FBT) fitting in conjunction with dual 1" Slip fitting ends. This component is constructed for seamless integration into various piping systems, allowing for easy disassembly and reassembly without the need for cutting or re-gluing pipes. It serves in applications that utilize components similar to 31-1605-00-R and is often used as a replacement in Jacuzzi Whirlpool Bath systems.