Strong, welded steel frames | Forged steel closure-type hooks with 1-Inch (25.4 mm) opening | 5-Inch (127 mm) wide aluminum alloy sheaves with self-lubricating bearings | 4000-Pound maximum pulling capacity | Outside diameter 12-Inch , inside radius 3-5/16-InchGreenlee's 4000-Pound capacity hook sheaves are 5-Inch (127 mm) wide aluminum alloy sheaves with self-lubricating bearings. Strong, welded steel frames. Forged steel closure-type hooks with 1-Inch (25.4 mm) opening. Select a sheave with a maximum rated capacity that meets or exceeds the cable puller's maximum pulling force.