I was watching a video and this guy had an altimeter strapped to his quad. I thought that was cool. I can only guess how high I fly and I am probably way off. I found this....ALTIMETER 1. It's $50. I have only read good things about this unit. Supposed to be very accurate. It weighs about 9 grams and has its own rechargeable battery. Now I know many of you already have altitude readout on your birds but also many have complained they are not accurate. I have P1s and no such data. They also have a 2 and 3 version. Some are made for rockets and not suitable for quads or planes. Worth a look. I should have mine Monday. I'll give a review if anyone is interested.