Ronstan Wire Block, Single, Ferrule Eye, 1" Sheave Dia., 1/8" Max. Wire, 990 SWL, 1.4oz.. Single blocks can double the power of a rope tackle using a cascading block system. Blocks up to 1" sheave diameter are stainless steel with nickel-plated brass sheaves. Blocks over 1" sheave diameter have removable anodized aluminum sheaves with Delrin bushings. Micro Kite Blocks are very strong, super-lightweight. They are ideal for flag halyards, dinghy outhaul block, cunningham, leech lines and any other small diameter line application.