Tendon boots protect the horse's sensitive legs from shocks and injuries when jumping. They support your horse's tendons and ligaments.
Tendon boots provide all-round protection for the horse's legs, especially when show jumping. It is therefore important that the boots fit perfectly. The horse tendon boots must not slip and should not restrict your horse's movement in any way.
However, as there is a risk of bumping into the poles when jumping, the boots must offer sufficient protection from bumps and shocks, especially at the front.
Tendon boots are usually hard shell boots or made of leather, lined with sheepskin or neoprene. The combination of hard shell and soft, protective lining prevents injuries. This way you can safely take any obstacle.
Whether or not you should put boots on all four legs of your horse depends on a few factors besides your personal preference. If your horse tends to touch the poles with its hind legs, it may make a lot of sense to protect it with tendon boots. As tendon boots also have a support function for the tendon, they can also be of good service if your horse is susceptible to injury.
You should always protect the front legs when jumping, not only because of contact with the poles, but also to avoid injuries from kicks from the hind hooves. Basically, it is better to protect all four legs with tendon boots.