Nautos 92083-30 &ndash; 6:1 Mainsheet System Blocks &ndash; Ultralight 6:1 MAINSHEET SYSTEM BLOCKS  ULTRALIGHT - 57mm SHEAVE Set of: 1 triple ratchet with cam cleat and aluminum central sheave & 1 triple block Working Load 990 lbs; breaking load 1400 lbs Sheave diam. 57 mm Recommended line: 5/16 to 1/2  Polyester double braid