Haven't actually used it, but looked into it when I heard of it a few years ago. It is a thin coating of Kevlar impregnated stuff, that you paint on to a horse's sole for added toughness. The reasons I chose not to try it was that it is a thin coating, providing added toughness, but not thickness or therefore much in the way of protection for thin soled feet. Also that they advised it shouldn't be used on the frog & heel bulbs, which IME is an area often more in need of protection than the soles. Also that you need a heat gun or hairdryer to set it. Also that being a hoofcare practitioner, I tend to do my horse's feet little & often - av. Once a fortnight. This means that it would need to be reapplied that often & not be economical. Oh & the other thing was wet environs & thrush - didn't want to use a product like that that sealed the hoof without treating thrush.
I've been looking into other alternatives besides boots and altho I haven't tried it yet either, I'm about to get some Vettec Sole Guard and EquiPak CS. They now come in smaller self applicator tubes, so easier to afford, no need for a special gun. The EquiPak CS treats and prevents thrush, with copper sulphate impregnated in it, then you put the Sole Guard over the top of it & over the whole sole to provide a protective & supportive pad. It is my horse's heels, what with wet environs over winter & thrush, little riding, they need protection & also extra stimulation so they don't contract, so if some gets rasped from the sole area when feet are trimmed, it shouldn't matter too much.
Another possible alternative, especially if your horse only requred short term protection, is Equicast. It's effectively a cast that goes on over the whole foot. You can put it over a pad, for extra protection and can inject fungicide or other thrush treatments into it.