Boss TU-10 Tuner
This is my first clip-on tuner. I've been using full-upgrade iPhone apps by Plusadd and Frozenape (their metronomes are excellent, too), the tuner in my Roland 40W Cube, or an old Sabine ST-1100 Autotuner I bought in the early 1990s. This Boss TU-10 is an excellent tuner and more convenient than my others. Tuning my Martin LXM and GPX1AE with it shows the tuning dead on coincident with the iPhone app tuners. This is a solid design, with rubber pads to protect your headstock. It's worth the cost. I'm also looking at pedal based tuners and I know now that Boss would be a very good choice, although there is a highly regarded strobe tuner,, sadly not sold by Sweetwater (why not?), that I also like.