Step Down Adapter Bore Diameter 1 1/4 in Bore Depth 2 in Adapter Outside Diameter 2 1/4 in Shaft Length 2 in Shaft Diameter 1 in Overall Length 4 1/2 in Adapter Type Step Down Screw Thread Size 1/4 In.-28 Adapter Material Steel Adapter Material Finish Black Oxide Adapter Material Grade ASTM A108 Bore Tolerance +0.003/-0.000 Screw Length 3/4 in Screw Material Steel Screw Material Grade ASTM A574 Shaft Tolerance -0.000/-0.003 in System of Measurement Inch