Acu-rite Quadra-Chek 220 micro-processor DRO. LCD display, radius/diameter measurement, angles & vertex, point to point distance, minimum/maximum distance between features, polar/cartesian measurement, incremental/absolute modes, RS-232, program storage, date/time stamp, linear error compensation, keypad & footswitch compatable, graphic display of measured features, geometric tolerancing, inch/mm, sound feedback.