Preston Pressure manufactures drop-in replacements for analog mechanical indicators in pitot-static testers. Altimeters indicate VSI (vertical speed) and are available in 35,000 and 50,000 feet options. Airspeed indicators available in 300 and 500 knot options, and display in mph and kph. Both instruments have a leak test function. For more information call (580) 286-3161 or visit www.prestonpressure.com.