Dixon SHD-Series Schrader Pneumatic Male Pipe Coupler SKU Body Size Threads Length 2SHDM2 1/4 1/4-18 NPT 2.22 2SHDM3 1/4 3/8-18 NPT 2.28 4SHDM3 1/2 3/8-18 NPT 2.55 4SHDM4 1/2 1/2-14 NPT 2.61