The first PW-CT-12 I got a while ago for my bass had a green screen, a mode button for tuning or metronoming and 180 degree screen flip. It worked well on the C and F tuned strings but rarely picked up the D and G. Playing the 12th-fret harmonic to tune them sometimes worked, but haphazardly. In a studio with other instruments making a noise the tuner failed totally to register anything at all. Best position for the tuner appeared to be right at the far end of the headstock, well away from the nut. My second purchase, shown here, has a white on blue screen, no mode button so no metronoming and 90 degree screen rotation. A better mix in my view. Performance is similar to the green-screen tuner. These tuners both really cannot cope with the two bottom strings on my basses and in fact the Snarks have proven in my experience to be much more capable and a better choice for tuning a bass. But who wants a ruddy satellite dish hanging off the end of his murder weapon?