Wiktionary
thumbwheel
n. A small thumb-operated wheel on a mechanical or electronic device.
Usage examples of "thumbwheel".
Beckwith could see by the thumbwheel that the weapon was selected to full automatic.
There was a device there, I saw it was made from two video game controllers, one with a couple small thumbwheels, another with a pistol grip.
His fingers began manipulating the thumbwheels, methodically running through the possible combinations -- 001, 002, 003.
He snapped the lid shut, scrambled the thumbwheels and worked his way to his seat past a short line of passengers standing by the lavatory door.