3-1/8″ TSO’d sensitive altimeters (with 3 pointers) in choice of new or recertified. The operating range is 0- 20,000 ft with the smallest increments being 20 ft. Includes Kollman window with barometric scale in inches HG that is adjustable to variances in barometric pressure. Static pressure port: 1/8-27 NPT. TSO C10b & TSO C88.