These SMC Pulleys are the mini of minis. Efficient and lightweight, its solid strength and efficiency tests to greater strengths than other pulleys in the same size and price range. It has the required prusik minding capability for use in a haul system (JRB Pulleys are now incorporated in our 4:1 Kit. A 1.20’’ nylon sheave and zinc-coated axle make any system run smooth. Simple to use and easy to carry into the field. Max Rope diameter for the CR is 13 mm. Max rope diameter for the JR and JRB is 9 mm. The CR pulley is a single pulley, while the JR and JRB pulleys are double pulleys.