Climax Part C-087-A, Aluminum, Set Screw Collar, 7/8 inch bore, 1 1/2 inch OD, 9/16 inch Width, 5/16-18 x 5/16" Set Screw: Shaft Collars: Amazon.com: Industrial & Scientific
Shaft Collar with Thumb Screw – Quality Lab Accessories
Hillman 1/8 I.D. x 3/8 O.D. Shaft Collar (10-Pack) 883551 - The Home Depot
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2920 Series Steel Set-Screw Collar (8mm REX Bore) - 2 Pack - goBILDA