An auxiliary performance control on a synthesizer, whose conventional usage is to add vibrato to the note or notes being played. On many keyboards the mod wheel is a large thumbwheel identical to, and alongside, the pitch wheel; it may or may not be sprung to return to the zero point when released. On others it may be combined with the pitch wheel function, usually in the form of a joystick. A notable implementation is the Roland pitch stick, which produces modulation when the stick is pushed away from the player. On a synth or keyboard that transmits MIDI, the mod wheel generates the MIDI Controller modulation (type 1) message.