Harken^® Bullet Block Single is designed for all control applications on smaller boats where up to 5/16-inch (8mm) line is used. Compact and lightweight with a sheave diameter of 1-1/8 inch (29mm), these blocks have a fast trim and release under both high and low loads. This low-friction Bullet Block leads control lines aft and is ideal for vangs, outhauls, cunninghams, spinnaker controls, traveler controls, barber haulers and more.