HARKEN 51 mm Wire High Strength Thru-Deck Block, 310 Product Type_Shackles Commonly 57mm fiddle blocks are

Commonly 57mm fiddle blocks are for jibsheets and vangs on small dinghies

Universal head allows one block to function as a front shackle

An integrated becket at the forward end of the car suits 2:1 sheet systems and the removable threaded pin allows easy fitting of alternate blocks and accessories

The sideplates are UV-stabilized

Stamped and formed to provide a smooth halyard lead and finished look to mast and boom slots they are carefully sculpted to eliminate line chafe and wear

HARKEN 51 mm Wire High Strength Thru-Deck Block, 310 Product Type_Shackles Commonly 57mm fiddle blocks areHarken 51mm Thru Deck High Strength Block allows lines through the deck and bulkhead. Harken's Lightweight, low friction blocks with high load composite bearings carry wire halyards and control line cascades. Side load balls reduce friction from twists or unfair leads on 304 311. 300 303 has thrust washers. Blocks open to allow passage of swaged wire. Hard Lube anodized sheave for strength and corrosion resistance. Cheek blocks include fasteners.