The Peterson 420 is a vintage strobe tuner that is designed for tuning guitar and other electronics instruments. It's got a classic sort of look to it, although I'm not sure what year this was originally made. The Model 420 tuner has a 1/4" input in the front for plugging your instrument in and it also has a built in power cord. The tuner has knobs in the front of it for choosing the note to tune to, as well as a finer knob for getting more specific if you need to. It also then has the strobe meter for monitoring where you're at. I don't own this tuner myself, as I've just used it in one of the studios that we've got on site here at the studio complex that I work at. These days a tuner like this isn't really necessary, as it's bulky and a bit more complicated than tuners are now. However, it's certainly an adequate tuner and will get the job done in just about any situation, although I probably wouldn't recommend using this anywhere outside the studio since it is older and it isn't really necessary to do so. I don't really have much background information on the Peterson Model 420 strobe tuner, so I can't speak to how much this would cost or how hard it would be to find one. I wouldn't recommend seeking this out unless you're after a really cool looking tuner to double as a display piece and tuner combined. If you're just after a tuner to get the job done, you can find plenty out there that do the job the same for most likely a cheaper price and that is more flexible. If you have your heart set on the Peterson 420, I will definitely vouch for it for what it is, as it's definitely an adequate tuner!