The Seiko Quartz Metronome Model SQ 50V has the accuracy that Seiko are famous for while being easy to set; just rotate the dial to the required beat.
It features a range of 40 to 208 bpm, audible tone adjustable between A4/Bflat4, adjustable volume, visual led pulse, an earphone jack and pop-out stand. It comes with a 9V battery.