The sail stop prevents the mains'l slides from falling out of the sail track when the main is doused at the end of the day. Original equipment on the Catalina 250, Capri 26, Catalina 270, Catalina 28, Catalina 34 and Catalina 36. The masts on these boats had the sail track drilled and tapped right above the sail slot entrance for this stop to be installed after the sail was bent on.