Used to prevent both grazing and cribbing, grazing muzzles can be a useful product.
Things to Consider:
Easy attachment -- Many grazing muzzles attach easily to your existing halter for a quick, comfortable fit.
Training -- muzzles work well to not only limit grazing, but to also discourage a horse from biting or nipping, and even help stop cribbing, where a horse chews on wood.
Material -- Chose a muzzle that is easy to clean, such as a nylon material, which is also lightweight and does not rot, since it will be getting wet when the horse drinks.