3/8" (10mm) to 3/8" (10mm) to 1/4" (6mm) Pipe T-joint

3/8" (10mm) Pipe to 1/4" Pipe T-joint

This t-joint has two quick-fitting sides for 3/8" piping, and one 1/4" on the "bottom" of the T-fitting. This fitting is normally used when you want to "T-off"  a 3/8" pipeline to another endpoint using 1/4" Size piping.