I just bought some Ice Horse® boots, and used them for the first time this morning. So far, I'm really pleased with them. I forgot to take my camera to the barn, so this picture is without horse, but gives you the general idea:
These are the model called Tendon Wraps (follow the link for a picture of these on a horse), and cover the area from below the knee to the pastern joint. There are other models, including a hock boot, a hoof boot and one that covers from the knee down to the hoof. Although I haven't used the boots long enough to know if they will be durable, they seem to be well-constructed and sturdy, and the straps are also sturdy. Maisie didn't seem to mind these at all when they were on, even though they are a bit bulky and heavy.
The ice packs are made with a non-toxic propylene glycol mix, which I would describe as having a somewhat gel-like consistency with beads when warm and more like crushed ice when frozen.
So far Maisie and I give this product a double thumbs-up!