A 3-5/8" diameter open design sheave creates a large diameter bearing race for the maximum number of ball bearings and minimum friction. Suitable for line to 5/8" diameter. High load Torlon bearings used in this block provide a 3,500 pound working load. They are more resistant to distortion caused by a constant high load as might occur when used as a jib halyard block.

To prevent the line from twisting or binding when used in a cascade or mainsheet system this block is supplied with a feature to lock the rotation of the shackle that is on top of the body of the block. With the use of an Allen wrench, tighten the set screw to lock the shackle in position. When used as a swiveling block, ensure the set screw is not tightened and the swiveling shackle can self-align to find the fairest lead.

Approximate Dimensions:
• Shackle pin diameter: 5/16"
• Sheave diameter: 3-5/8"
• Maximum line size: 5/8"
• Bearings: Torlon
• Safe working load: 3,500#
• Shackle pin diameter: 5/16"
• Shackle width, inside: 5/8"
• Shackle depth, clearance between pin and bolt head: ~9/16"