The Guyatone PS3 Phase Shifter is a pedal suitable for use with any electronic instrument, but is one that I've only used with electric guitar. The pedal has a 1/4 inch input and output, and is said to be based upon the MXR Phase 90. The pedal isn't rack mountable as it is a stomp box.
In terms of utilization, the Guyatone PS3 Phase Shifter couldn't be too much easier. The pedal only has two parameters to work with for depth and speed, which are two parameters widely seen on a phase shifters. Even if you don't have experience with phaser pedals, this makes it as easy as possible to learn how to use one and to understand everything going on here. A manual isn't necessary, although I haven't seen one for the PS3, so I can't say anything about its make up.
In terms of tone, Guyatone PS3 Phase Shifter has a lot to bring to the table. I've used the pedal inside of the recording studio with a Fender Strat and a '76 Fender Twin Reverb, so I'm getting a pretty good idea of what the pedal truly sounds like. I'm a big fan of the way the PS3 sounds, as even though there are only two parameters, I still find it possible to get a number of great sounding phaser tones. I'm not the type of player who used phasing on everything, as I tend to use it sparingly here and there if at all, so I find that the Guyatone PS3 Phase Shifter suits my needs perfectly. I've used all sorts of different phase pedals out there for recording sessions, and in terms of the sounds that this can get, it is up there with the best of them.
If you're in the market for a phase shifting pedal, you certainly have a large amount of pedals to choose from. I'd definitely recommend checking out other models like the Boss PH-3, MXR Phase 90, and T-Rex's Tremonti Phase, as all of these are more than adequate choices. Having said this, the Guyatone PS3 Phase Shifter is also worth checking out, as even though it doesn't have as much versatility as a pedal like the Boss PH-3, it offers up a reasonably priced pedal with a ton of great tones. Definitely do your research before you choice a phaser pedal, but don't forget to check this on out...