This is an upgrade for the Yaesu FT-817 amateur radio. Print the new knob and then remove the rubber collar around the original knob. After the collar is removed unscrew the set screw with an allen wrench. Once the set screw is removed you can pull the original knob off. Slide the new crank knob onto the tuning shaft and then screw in the set screw. Finally replace the rubber collar on your new knob and enjoy your radio.