I thought this was a neat idea on the surface, but after digging into the “tech” they mention a little…
it’s just a PVA evaporative “cooling towel” made into a boot.
Evaporative cooling is not very effective in any sort of humid climate, there’s just too much moisture in the air already. I think claiming that they provide 20-30 minutes of cooling is a bit of a stretch, it would highly depend on the environmental conditions plus the horse’s starting skin temp and the soaking water temp. Ice water for soaking would be most ideal, but then you need to have ice on hand and if you have that, why wouldn’t you just ice the horse’s legs?
Evap towels are basically useless where I live (near Houston), you might feel a little cooler for the first 2-3 minutes of wear but after that it’s just a warm, clammy towel. 