Been testing a Belite ASI for ultralights for awhile, 20 mph to 80 mph in 5 mph increments. Not to impressed. Have now tried the 2-1/4" Belite ASI, VSI, ALT, powered by 9v battery and it works great and I can report it is good unit for those wanting a light weight, just a few ounces, unit that provides the ASI, VSI ALT. The alt is in mph and starts at about 20 and goes up to at least 100, shows in 1 mph increments and seems very precise. the ALT is in feet and can be set for Barometric pressure like normal ALT and VSI works like normal VSI, not like the VSI in my cell phone foreflite program. More info to come as we test it more.