Rutgerson three - sheave pulley with jammer Smooth pulleys for high loads. The sides and discs of the Rutgerson blocks are made of high - strength composite material. Rutgerson Block dreischeibig mit Klemme Model Ø mm Axis - Ø mm Cordage - Ø mm Loadkg Breakagekg Weightg Block Serie 300 35 4 3 - 7 450 850 153 Block Serie 500 50 5 6 - 10 700 1.250 300 Block Serie 600 60 6 8 - 12 1.150 2.100 490