Used to secure jibs to the wire forestay. Locks positively over the stay with a sliding piston that closes a hooked end.
These Ronstan snaps can be installed simply by inserting a self-tapping screw (included) into two plastic "ears" that fit over and behind the luff reinforcement. Soaping the screws before installation reduces breakage. These are great for drifters. Grommets are not necessary.