Sailboat Dinghy 57mm 2 1/4 Inch Deluxe Ratchet Single Swivel Shackle Block Small Boat Block Master RAS-0501F Master Deluxe Automatic Ratchet Block Our exclusive patented design offers both full automatic and manual modes in simply one block. The new design simplifies all control switches to the one. The unique Master Automatic Ratchet Block can easily switch among two modes by single switch. The Sheave automatically changes from off mode to ratchet mode when loads increase. Sailors are available to control lines whenever they need the ratchet function. Manual switch to ratchet, off, or always-on modes by controlling button. The high strength composite sideplates are hybrid with composite and 316 L Stainless Steel. They are lightweight and strong to provide excellent weather-ability for maximum protection. NC machined sheaves with 8 faces give Master Automatic Ratchet Block extremely holding power to line movement. A patented Lock-up system can be easily engaged to in either or two directions, or free to swivel. Exclusive composite Ball Bearing provides sheaves with good rotation and less friction. The most advanced Master ratchet blocks are available in 57mm and 75mm with variable configurations. Specification: Brand: Master Part Number: RAS-0501F Sheave Ø (mm) 57 mm Sheave Ø (in) 2 1/4 in Length (mm) 115mm Length (in) 4.53 in Weight (g) 162 g Weight (oz) 5.7 oz Maximum line Ø (mm) 10 mm Maximum line Ø (in) 3/8 in Maximum working load (kg)250 kg Maximum working load (lb) 550 lb Breaking load (kg) 500 kg Breaking load (lb) 1100 lb •Do not use Master products to human suspension!