3/4 Inch Zinc Clear Low Carbon Steel Solid Shaft CollarStandard style (SC) shaft collars use a hardened set screw to penetrate the shaft so as to achieve grip This penetration yeilds light duty benefits for applications like thrust collars, abor spacers, sprockets hubs, bearing holders, and shaft protectors SC collars do not work well when th shaft is harder than set screw or when penetration marks on the shaft are not desirable Black oxide coating will slightly increase friction and holding power in some