Harken designed their low-friction Bullet blocks to lead control lines with minimal friction. They are compact and lightweight, with fast trim and release under high or low loads. A range of styles lets these blocks adapt to almost all control line applications. Wire Bullet blocks use roller bearings to carry higher loads and features hard lube-anodized aluminum sheaves for strength and corrosion resistance. Mast exit blocks with cams are used for halyard controls and under boom mainsheets.