These Sail Track Stops contain your sail slides in the track, and unscrew for removal of the sail.When its time to lower your sail, you can rely on Davis Sail Track Stops to hold your sail and its slides in place on the mast and boom.Large knurled wheels are released with ease. Made of heavy-duty, black anodized aluminum and marine grade nickel plated brass. Flat stops come with lanyard holes.Key FeaturesHold your sail and its slugs in place on the mastLocks in place with the knurled thumb screwMade of heavy-duty, black anodized aluminumMarine grade nickel-plated brassLarge knurled knob is easily releasedFor mast or boom2352 Flat-large stops for spars with flat grooves; 3/4" diameter x 1"W x 1/8" thick (19 x 25 x 3mm)2350 Round stops fits almost any slotted spar with round luff groove; 1/2" diameter x 7/8"L (13 x 22mm)2351 Flat-small stops for spars with flat grooves; 3/8" diameter x 1"W x 1/8" thick (11 x 25 x 3mm)