Harken^® Micro Block Upright is a compact, low-friction, lightweight block system with a smaller sheave diameter of 7/8" (22 mm). Designed for all control applications on smaller boats where 1/4" (6 mm) line is used, this block has a fast trim and releases under both high and low loads. Delrin^® ball bearings ride on flat races for ultimate low load performance yet they are capable of working loads of 200 pounds (91 kg). Easy maintenance: just flush with mild soap and fresh water. They are ideal for use on smaller dinghies, and lightly loaded control lines on boats of all sizes. Use for traveler controls, cunninghams and outhauls, vangs, barber haulers, flag halyards, lead car return tackles and leech cords. These are most frequently used as a line turning block at the base of a mast.