These were advertised on banggood for the Hubsan x-4 but they fit on anything that uses the same size shafts, such as the jjrc 1000a, eachine x6, jjrc super voyager, ls 124, and many others. They make these quads super quiet but absolutely kill the flight time and performance! Personally I wouldn't recommend these but if you'd rather have a short quiet flight then a loud long one these are for you. Thanks for watching and please subscribe!
Link to purchase from banggood (pack of 4 $2.69 from USA warehouse!):