Harken System AA CB Battcar w-10mm Stud13 mm CB Battcar 10 mm Stud A Harken Battcar system along with full length battens helps raise, douse, and reef with ease and acts as extra crew if youre sailing shorthanded. Battcar systems outperform in mast or in boom furling, cost less, and you dont need to recut your sail. The one piece solid aluminum construction is lightweight and strong. The free rolling ball bearing cars let you hoist and reef the main quickly on all points of sail.