These are perfectly sized for use with 1/4" line. Catalina Yachts uses them for 5/16" line also. When used with 5/16" the line does touch the smooth frame on either side a bit. Not enough to cause a problem, but still it does touch. The advantage is, the blocks only require a narrow slot in the mast, much smaller than a Harken exit block for example.

Mounting hole size:
• Height: 2-1/8"
• Width: 9/16"

Fastener hole spacing center to center:
• Top to bottom: 1-3/4"
• Side to side: 1"

Fastener hole size:
• 3/16"

Overall size at mounting flange:
• Top to bottom: 2-1/8"
• Side to side: 1-5/16"

Sheave dimensions:
• Diameter: 1-1/2"
• Width: .40"
• For line diameter: 1/4" (was often used by Catalina Yachts with 5/16" line)

1) In the photo above, the block is oriented as required for use at the base of the mast of the Catalina 22 and Catalina 25. The main and jib halyards exit below the sheave. When installed as the spinnaker or jib halyard block at the top of the mast on a Capri 22, it is installed with the sheave near the bottom of the block with the line exiting above the sheave.

2) The earliest Capri 22 used a slightly different block for a short time (offered below listed under "may we also suggest").

3) If you Catalina 22 or Catalina 25 was built before 1986, it was originally equipped with external halyards. If it currently has internal halyards, a previous owner upgraded them from external to internal. In that case, we have no way to know which exit blocks were used. Be sure to check all dimensions against the blocks you are replacing before you order to ensure a proper fit.