The Harken 40mm Switch Non-Locking Headboard Car Assembly, clear anodized. Harken's award-winning, patented Switch T-Track Battcar system halves the stack height of mainsails on large yachts by stacking cars side-by-side on top of the boom, making it much easier for crew to fit sail covers and connect or disconnect halyards. Cars are Hard Lube-anodized and UV-stabilized for durability. Cars run on low-friction plastic slides.