POWERTEC 70126 Inlet Flange, 4-Inch Designed to attach easily and securely to machines for connecting to dust collection systems Pre-bored mounting holes for easy and secure installation Tough, durable ABS plastic material Flange diameter measures 5-9/16-Inch 4-Inch nominal end measures 3-59/64-Inch OD. And 3-23/32-Inch I.D.