The tuner itself has a flat pick edge. You simply take the tuner, turn the dial at the top of the unit (called the "data wheel") to the note you''re aiming for, pluck the string at the 12th fret and hold the LEDs above the string. When a string is out of tune, the two lights rotate around each other on nearby points of the string, in a kind of lazy wobble. The closer you get to the appropriate pitch, the faster the lit points chase one another, and the closer they get.
When the string is finally in tune, the two lights stop moving and hover right next to each other. Rotate the dial on the tuner to change the lights'' pulsation rate, tune the next string, and match up the lights. Rinse and repeat. It''s a fairly user-friendly idea, and anyone who has a passing familiarity with a strobe tuner will quickly grasp the concept.
The first time I used this - having not heard anything about it - I initially thought that this little handyman was gimmicky. I''d believe its utility when I saw it. I went through my six strings, rechecked the A and low E, and strummed a chord, and was actually surprised; I hadn''t known what to expect, but the chord rang true. I rechecked the guitar using a variety of other tuners, and they all confirmed the success of the S.O.S. tuner.
My biggest concern with this device, knowing myself, is its durability and the prospect of losing it. It is about as thick as 6 picks put together, and probably weighs less than that. The outer case is a durable plastic, but this is something that could easily be misplaced and/or stepped on. But if you take care of your stuff, that should be a minor concern, if at all.
One other minor note - the S.O.S. tuner is only able to handle guitars in a standard tuning, so if you want to tune your guitar to some incredibly exotic setup, you''re out of luck. But really, what do you expect for under 15 bucks?
All in all, this is one slick, inexpensive way to keep you sounding great. The S.O.S Tuner is the stocking stuffer I would''ve gotten if my parents were gearheads too!