Safety features include removable drive handle and fully enclosed drive mechanism. Drive Reduction 16 to 1: To ensure that minimum effort is required to turn the handle. One complete turn of the handle advances the platen only 19mm (3/4") Framework: Aircraft quality aluminium. Steel Rollers : 100mm Diameter Electrolyses Nickel or Chromium Plated. Upper Roll supported in Spherical Seated Ball Bearings 42mm (1 5/8 ) Diameter. Lower Roll supported in Deep Groove Ball Bearings 52mm (2 1/16 ) Diameter. 0 to 40mm Adjustment of Rolls. Drive Mechanism: Running on Maintenance Free Sintered Bronze Bearings. Memory free Laminate Platen. High Tensile Fine Thread Tightening Screws running in Phosphor Bronze Nuts. Attractive Coloured Anodised and Powder Coat Finish to all Aluminium Parts. The A3 model can be modified to facilitate easy disassembly & assembly of the platen supports for suitcase storage and transportation.