Anti Biotic Zone Reader (Prism type)   The instrument is unique in design and measures the diameter of the inhibited zone to 0.1 mm within the range of 0 to 35 mm. Light from a source in the base passes up through the transparent and semi transparent portion of the agar.-agar, then to a reflecting mirror supported by an arm above the unit. The mirror reflects the light to a glass prism mounted at the front of the unit and the magnified image of the prism. The unit is suitable for operation on 230 V, 50 Hz, Single phase AC Supply.