PULLEY 50mm DIA NYLON 2xSHEAVE FRAME W/HOOKS
The IEC 'Pulley in Sheave' is one of IEC's oldest items and dates back to the 1960s, but several changes to design have occurred over that time. The original pulleys were machined in their thousands from 2" diameter solid aluminium bar and the sheaves were sand cast aluminium - all filed smooth by hand. The pivots were needle points. I know all this because I personally made them (Bernard Hodson).
All IEC pulleys today are moulded in Nylon and they run on silversteel shaft. The frames or sheaves are pressed aluminium and the hook each end is very strong. The sheaves are held together with screws and nuts so that they can be repaired or modified by the instructor.