This little ring can help you adjust the ressistance of your remote control sticks by adding tiny rubber bads on the grooves. you can add probably up to 5 bands for each direction and you will have to use some double sided tape to mount it on the controller!
installation takes about 2 minutes and no technical skills required at all.
this can help you get better shots by moving the sticks very steady and slow even if your fingers get a little "shaky" when flying far or risky or just in cold weather :-)
please note that one side of the ring is a little thicker than the other - this side goes towards the outside of the controller and thin side goes towards the center of the remote control
Fly safe!