POWERTEC 70190 Y-Fitting, 4 x 2-1/2" Tough, durable ABS plastic material Simple and quick to install Provides a multitude of applications Two 4-Inch nominal ends measure 3-15/16-Inch O.D. and 3-45/64-Inch I.D. 2-1/2-Inch nominal end measures 2-15/32-Inch O.D. and 2-5/16-Inch I.D.