Portable tuners are great, but both clip-on and plug-in models are clearly designed for electric guitars and basses. Korg’s CM-300 ($15.99) is a piezo contact mic designed to clip onto wind instruments, violins, and other non-pickup-equipped strings. Its purpose is to isolate the sound of those instruments for greater tuning accuracy. Though it’s designed to mate with Korg’s own tuners, it comes with a standard 1/4″ plug (on a nice long lead), making it compatible with just about everything out there.
$15.99 MSRP korg.com