Used just for a test. Price of the new ones is 500$ Price for sale: 80$ It is designed to allow users to repair easily and All vibrations are able to adjust. Supplying optional parts with can be mounted on almost Multi-roters. Material: aluminium 6061-T6 Total weight per one pair : 290g (1pcs 145g) Size : Height(48mm) Width(27mm ) Length(105mm) Operating Temperature: (-5¡ÆC~40¡ÆC) (23¡ÆF~122¡ÆF) Operating range: 90 (degree) Weight Test: 80kg (The SE-Retracts-Pro V2 is recommended for less than 20kg Multi rotors) Required: Bec 5V~6V 3A (Max 7.4V) (Necessarily require a power 5V~6V 3Amp) .
Hi, you don't need controller, you just plug into the receiver. Yes, they work well. I don't need them, because I didn't finish the project for which I bought them.