Part No. 128 Sheave (mm)38 mm Sheave (in)1 1/2 in Maximum line (mm)10 mm Maximum line (in)3/8 in Maximum working load (kg)272 kg Maximum working load (lb)600 lb 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.