Starboard sail stop for B&B masts and track (sold each). CNC cut from UHMW starboard plastic with a 3/16" hole for a #10 fastener. We recommend installing with a #10-32 machine screw drilled and tapped into the mast with a bit of lock-tite. In operation the sail stop "snaps" into position on the mast due to the concave section on the backside. Rotate the sail stop 90 degrees to the mast to load or remove the sail slides from the bottom of the track.