This is a capo made by Kyser + Classics, who make the ubiquitous black capo that everybody has most likely purchased at one point or another, considering how cheap and relatively reliable they are. This capo looks pretty similar to that one except for one huge difference.
This capo is called the Drop D capo, but I'm not sure why. The only unique feature of this capo is its design, which when applied across the strings, leaves the low E string untouched, giving you an open E string regardless of where you apply the capo. This can be really useful in coming up with open chords, as well as different variations of E chords major, minor, dominant 7th, etc.
The only drawback that this capo suffers from is a lack of practical application. If you leave the guitar tuned to E, this capo will only be effective if placed on a few particular frets. My personal favorite is the fourth fret, as it has notes that fall in the E major chord. The 3rd fret works for minor chords but can be kind of limiting to a player. The 7th fret is a good choice as well. If you tune the guitar down (or even just the low E), other possibilities emerge, but then it also starts to get really confusing.
The main thing about this capo that is interesting is that it basically forces a guitar player to think outside the box and come up with new, creative ways of playing chords. I think overall this is a really good thing, as it will enable players to explore chords that are usually outside of their comfort zone, with or without a traditional capo. However, unless you really take the time to experiment, this capo will have limited use for you, most likely. The usefulness of the product depends mostly on how much you are willing to let it be the deciding factor in your playing, that is, taking the time to work around this capo. A really cool idea but one that demands a commitment.