Use Bullet blocks to lead control lines with a minumum of friction. A wide range of variations let these blocks adapt to almost all control line situations. Classic blocks feature stainless steel sideplates and Delrin ball bearings Wire blocks feature a Teflon impregnated Hardkote anodized aluminum sheave Shackle pin diameter: 3/16" Use for outhauls, vangs, barberhaulers, cunninghams, traveler controls, furling line leads and flag halyards