They act as a support for the tendons and help prevent injuries, but the front of the boot only has straps across it. These boots are designed for horse that jump and are not allowed to touch the fence. If they do knock the fence with their bare legs, it stings much more than having a covered boot protecting them. The idea is that the horse needs to pick up his legs more. These boots do come in front and hind, though I suggest not purchasing them unless you are a serious jumper.
Polo wraps are a great support, like galloping boots.
You will need to learn how to put them on properly. Ask your instructor, or vet. These have great support and offer the horse to move freely under them. If the bandage is too tight across the tendon, you will injure the horse. Also, if the wrap is too loose, you might endanger your horse of tripping over it and hurting himself.