The MetroPitch is solid contender in the pocket-sized tuner/metronome category, offering a jog-wheel and 1/8-inch headphone jack, along with a wide calibration range.
Made by Korg
The GA-40 has been a staple of Korg’s tuner line-up since 2005. It’s a basic, inexpensive and rugged little unit with a few nice-to-have extra features. Intended for use with guitar and bass only.