The range of a prism results from, among other accessories, its coating and the glass geometry. A number of Original prisms from Leica Geosystems have a special coating on the reflective surfaces – the Anti-Reflex Coating, and a copper coating on the reverse side. Without these, the range of distance measuring, ATR and Power search would be reduced by up to 30%. The workmanship and the durability of the copper coating are decisive for a long life. The reflector glass dimensions, the position in the holder and with it the areal orientation, are important for measuring accuracy.