Usage (there may have been others of which we are not aware):
• Catalina 375: Mast collar blocks, 4 per boat
• Catalina 385: Mast collar blocks, 5 per boat
• Catalina 445: Mast collar blocks, 5 per boat

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: 3/8"
• Sheave diameter: 3"
• Line diameter: 5/8"
• Overall height (w/o shackle): 5-3/8"
• Bearings: Needle bearings
• Safe working load: 3000 pounds