HARKEN 57mm Self-Contained Sheave, 2760 Blocks_Fiddle It is used for main

It is used for main and jib sheets on course racing keelboats

Commonly used for spinnaker sheets

Ronstan designs and manufactures world-class blocks and pulleys for all types of sailing

The martensitic group includes very similar 17-4 PH and 15-5 PH alloys

HARKEN 57mm Self-Contained Sheave, 2760 Blocks_Fiddle It is used for mainThe Micro, Bullet, and Big Bullet sheaves are Delrin with Delrin ball bearings. They are scored for rope. 16 mm sheaves are Delrin and feature stainless ball bearings that ride in a grooved race. Midrange sheaves come in either Delrin or aluminum for wire. Wire sheaves are Hard Lube anodized aluminum that rides on high load composite bearings. Ball bearings in the 38 mm (1 1 2") and 51 mm (2") sheaves minimize friction. The 25 mm (1") wire sheave uses