The Diaz Tremodillo Tremolo is a pedal useful for any electric instrument, although specifically designed for electric guitar. This is what I've used the pedal for, although I definitely wouldn't doubt it's ability to be a great pedal for keyboards or otherwise. The pedal has basic characteristics, with 1/4" jacks for input and output and a nine volt power supply jack. It's not going to be rack mountable in any way as it's a stomp box to be controlled by your foot.
It's not hard to operate the Diaz Tremodillo Tremolo, although there are some unique features here to be aware of. It's got knobs for controlling rate and dwell parameters, the latter of which is the equivalent to depth, while it then has foot switches for both engaging/shutting off the effect, and the other is a unique button for doubling the speed, which is something I haven't seen anywhere else. It's very easy to use, so you shouldn't require the assistance of the manual.
The Diaz Tremodillo Tremolo is definitely up there with some of the best sounding tremolo pedals I've used. It's definitely a traditional tremolo, reminding me a bit of vintage Fender amp vibrato. I was an engineer on a recent session where this pedal was being used, and was almost immediately impressed with the depth of the effect, despite only a minimal amount of controls. There are some pedals out there with more control and a comparable high quality sound, but you're going to be hard pressed to find one you could say sounds better than the Tremodillo.
While expensive for a compact pedal of this kind, the Diaz Tremodillo Tremolo pedal is made for professionals looking to add a top tier trem pedal to the mix. There are cheaper models out there that I'd recommend checking out, but if you're looking for tone regardless of price, Tremodillo needs to be near the top of your list of pedals to try out. I don't know too much about Diaz, but judging on my use with Tremodillo and a few of their other pedals, they have a very good idea of what they're doing!