 A number of variations are available, including an instrument that uses strings for strumming or picking, to trigger notes, whereas the pitch of the notes is determined by the keys that cover what would be a "fretboard" in an ordinary, stringed guitar.Starr labs recently introduced the Z5S, a simpler and less expensive version of the Z6S.MIDI guitar controllers have regained popularity due to the Z6 model, possibly because of its usage by Rob Swire of Pendulum, who uses it on songs where he is required to perform vocals.