A Harken® Battcar system along with full-length battens helps raise. douse. and reef with ease and acts as extra crew if you’re sailing shorthanded. Battcar systems outperform in-mast or in-boom furling. cost less. and you don’t need to recut your sail. Slider Battcars offer a lightweight. cost effective way to raise. reef. and douse mainsails. Hardcoat-anodized aluminum cars slide on low-friction plastic inserts. The compact car size translates into reduced weight and stack height.