Selden Mast Slide Plastic 9/16" is a slide used to secure mains or mizzens to their spars and make lowering sails easier. Sail slides are typically secured ahead of the boltrope and inserted in the mast slot instead of the rope. Secure this plastic slide to a sail with webbing, webbing and grommet, shackle and grommet, or just a shackle. Selden slides also keep the sail stacked in the slot when a sail track stop is used. Slugs and slides are generally installed every 26" along the Luff edge and every 18" along the Foot edge of a sail.