I've been riding twice recently with a ski instructor pal who puts these boots on her horses' front feet instead of horse shoes. It's a New Age approach. Over the years I've seen a lot of gimmicks with horses.
Got to say these seem perfect for a ski town, because the boots are about as hard to put on a horse with overgrown feet as ski boots are for me to get on right. But her horses seem to be comfortable with them on, even walking on a gravel road for two hours.