Clock Tensioning Wire Brass Clock Tensioning Wire Brass is an assortment of 10 different diameters of Brass Tensioning wire. This Tensioning wire is usually used around wheel shafts or pillars to provide lift, or the return of levers. Diameters included in the assortment range from a gauge 18 to a gauge 27 (1.02mm to 0.36mm). This is a must have assortment for anyone attempting the repair of old clock movements.