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