POWERTEC 70123 O.D. Splice, 4" Designed for connecting to two 4-Inch diameter hoses together Each O.D. accepts most 4-Inch dust collection hose A middle section with greater diameter for easy assembly Tough, durable ABS plastic material Both 4-Inch nominal ends measure 3-31/32-Inch O.D. and 3-11/16-Inch I.D.