Bore: 1/2" Outer Diameter: 1" Width: 1-1/2" Screw: 1/4-28" RC-050-KW-4H@90 Solid Rigid Coupling 1/2" ID with Keyway Black Oxide Finish Oxide Bore: 1/2" Outer Diameter: 1" Width: 1-1/2" Screw: 1/4-28" Weight: 3.8 oz each 4 Screws Set Screw Couplings are the most cost-effective Rigid Coupling, stock in black oxide however, we can quote stainless steel rigid couplings on request. Standard sizes 1/4" to 2" Inside Diameter (ID).