For important medieval construction sites such as that of the fortified castle of Guédelon currently carried out in the Yonne department, a drum winch is frequently added to the traditional lifting devices to form squirrel cages that increase their pulling power. These cages, usually 13 to 16.5 ft (4 to 5 m) in diameter, are single-drum (i.e operated by a man) or double-drum. They function thanks to the muscular strength of the legs of the workers that - more resistant and more powerful than that of the arms - enable them to lift loads of 1,102 to 2,204 pounds (500 to 1,000 kg) in a single rise.