Check the listing for details. Pair Used Schaefer Pulley Block 2" (50mm) Single Blocks 7/16” Line Fast Ship. Condition: Used. Listed at 37.99 USD. One pair Used Schaefer Blocks, 2" (50mm), Single Block. Condition is "Used". Schaefer 2” single Block 2" (50 mm) Single Block Specifications · 2" Single Block · Diameter 7/16 Inch · Direction Any · Integral Cleat No Integral Cleat · Length 4 Inches · Mount Type Fixed · Ratchet Non-ratcheting · Sheave Diameter 50mm · Type Single · Weight 4 Ounces Product Overview Schaefer 2 " Single Block is used for main and jib sheets on course racing keelboats, scows and dinghies with large mains. Often used for spinnaker halyards and sheets on small offshore boats. .50mm sheave. Delrin ball bearings. 7/16" line diameter. Cheek is made from aluminum with stainless steel straps. One block has Delrin plastic Sheeve, one block has (I believe) An aluminum sheeve.