Harken Bullet Thru Deck for Wire w-Stainless Coverplate29 mm Wire Through Deck Bullet Block Stainless Steel Cover Low friction Bullet blocks lead control lines aft. 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 feature hardcoat anodized PTFE impregnated aluminum sheaves for strength and corrosion resistance.