Check the listing for details. 57mm Deluxe Single Swivel Shackle Block - Master SPB-5701F. Condition: Brand New. Listed at 41.44 USD. Product Specifications 57mm Deluxe Single Swivel Shackle Block - Master SPB-5701F Sheave Ø (mm) 57 mm Sheave Ø (in) 2 1/4 in Maximum line Ø (mm) 12 mm Maximum line Ø (in) 1/2 in MWL / BL (kg) 280 / 1150kg MWL / BL (lb) 617 / 2530 lb Product range – Deluxe ball bearing blocks (including high-load models) Master Deluxe ball bearing blocks are available in 29mm, 38mm, 57mm and 76mm sizes and multiple configurations. The range featuresDelrin or Torlon low friction ball bearings combined with a self-lubricating Acetel bushing for speed and minimal friction,316L stainless steel and UV stabilised, stiff glass fibre reinforced Nylon composite side plates for robustness and looks,standard or high-load models in the 76mm version,Torlon ball bearings and a stronger, forged stainless steel shackle for the high-load models,locking mechanism so that the shackle in the “single swivel shackle” models can either rotate freely or be locked in position (only from 57mm),becket pin which is easy to remove or lock into the keyhole with no tools,adjustable cam cleat arms for an optimal exit angle of sheets (only from 57mm).