Specifications 1L308HD UPC Code: 662786004537 Total Width (in.): 1.000 Series: Signature Weight (lb.): 3.23 Material: Steel Finish: BLACK OXIDE Bore Size (in.): 3-1/2 Screw Size: 1/2-20 x 1-1/4 Screw Type: SHCS Smooth bore protects shafts from damage Superior holding power over set-screw type collars Offered in High Strength, Low Profile and Heavy Duty styles Stocked in a variety of materials 1-Piece Clamp-Type Shaft Collars are for use on standard round shafts, hard or soft, as well as on thin wall tube or over a split hub. Precision machined, non-marring, easy to adjust, with high clamping power, they are stocked in the following materials: Steel Stainless Steel Aluminum Nylon Delrin Offered in three styles: High Strength: Clamp screw does not protrude beyond the outside diameter (OD) Low Profile: Clamp screw protrudes beyond the OD Heavy Duty: Uses larger clamp screw and has larger OD for 2X holding power Standard Series offers economy-priced versions of low-profile styles (31LXXX and 31SXXX parts).Shaft Collar Basics VideoView CAD File