It is used on all Catalina 25's regardless of year and most Catalina 27's. The latest Catalina 27's built used a different boom and gooseneck and therefore a different tack arrangement. A defining characteristic of the late model Catalina 27 boom is the tab extruded into the tube which extends below the main body of the oval. If your boom has the tab, you have the late model boom.

• Diameter: 1/4"
• Length, overall but not including the head: 1-3/4"
• Length, grip: 1-5/8"