This is a substantial piece of equipment intended for permanent siting in a clinic. The framework is rigidly made of light alloy with tubular steel legs and adjustable feet. All metal parts have a silver hammer finish. The counter balanced head-block is of the standard Harpenden ball bearing mounted design allowing accurate readings to 1mm. In addition, it has a secondary carriage, fitting with an anti-reverse carriage lock, in order to compensate for upper leg length variations. An adjustable foot rest allows for lower leg length variations.