Self-contained sheaves are designed for sailors to use in custom applications. Micro, Bullet and Big Bullet sheaves are made with Delrin ball bearings and scored to provide friction for rope 16mm AirBlock sheaves are Delrin and feature stainless steel ball bearings that ride in a grooved race Mid-Range sheaves come in either Delrin or aluminum for wire. Wire sheaves ride on high load composite bearings and are Hardkote anodized aluminum with Teflon impregnation Ball bearings in the 1-1/2" and 2" sheaves minimize friction. The 1" wire sheave uses low friction washers for this purpose Two 160 sheaves make up the 161 dual sheave to divert a line which must turn in either direction