Sailboat Hardware 57mm 2 1/4" Double Swivel Shackle Block BB-0503F Master Windrider 57mm blocks are specially designed for high-load and dynamic application. Available in comprehensive range of sizes for different rope diameters. An exclusive Face to Face locker system can be easily engaged to position shacke in either of two directions or just free to swivel. A locker system also can take more loads then traditional ways without damaging the block and hassle. Patent pending in Australia, US, UK, France, Netherlands, China, Germany, and Taiwan. US, Taiwan, China Design Patent. •Do not use Master products to human suspension! Specification: Brand: Master Part Number: BB-0503F Sheave Ø (mm) 57 mm Sheave Ø (in) 2 1/4 in Length (mm) 122 mm Length (in) 4 4/5 in Weight (g) 173 g Weight (oz) 6.1 oz Maximum line Ø (mm) 10 mm Maximum line Ø (in) 3/8 in Safety working load (kg) 370 kg Safety working load (lb) 814 lb Breaking load (kg) 1200 kg Breaking load (lb) 2640 lb