Simplex trench braces are designed for use with standard schedule 40 pipe. Screw end models SE-12, SE-16 and butt end model BE-25 use 1 1/2" diameter pipe. Model SE-18 and butt end BE-35 use 2" diameter pipe. Dimensions assume the use of both screw & butt ends together as an assembly. Screw & Butt Ends sold separately.