It says it's a "stand alone unit". You plug it into your receiver, fly the plane, then look at the reading afterward. I think it tells you the max speed during that flight. Well, this is what it says:
For standalone mode, simply plug the sensors into a spare receiver channel or small battery (3V to 16V) and fly your model. Then, when you land, your maximum altitude or airspeed will display on the built-in 7 segment LED. For example, if you flew to 281 feet, the unit will display “2 – 8 - 1” repeatedly. No configuration, additional equipment, or computer required!
It uses it's own Pitot tube to measure variations in pressure, then displays it on the 'screen'. So cool! Just like a real plane
