Ronstan Nylatron Sheave Box - Single Upright Lead Block. When mounted in an inverted position are frequently used as upright leads. Specifications for Ronstan Nylatron Sheave Box: Manufacturer: Ronstan Color: Black Features of Ronstan Nylatron Sheave Box The external tabs can be formed to fit the spar profile before fastening Applications: Typically used in dinghy spars for control lines such as outhauls Materials: Nylatron sheave Grade 316 stainless steel load housing : Sheave : 22mm(7/8") Max. Rope : 3mm(1/8") Max. Cable : 3mm(1/8") Fastener : 5mm(3/16") M.W.L.: 160kg(350lbs) B. L.: 350kg(700lbs) Weight: 30g(1.1oz) Package Contents: Ronstan Nylatron Sheave Box Ronstan RF453: Nylatron Sheave Box - Single Upright Lead Block