You must be familiar with local regulations when entering a competition. Strict rules are usually in force with regard to fly bonnets. A fly veil is usually prohibited in any case. This applies regardless of the equestrian discipline. Only fly bonnets that do not extend beyond the eye line are usually approved. You may also not attach the fly bonnet to the noseband. This is to guarantee the undisturbed movement of the horse's ears.
In all competitions that take place outside, ear bonnets with noise protection are also prohibited. This type of fly bonnet is only permitted for indoor competitions. You must make sure that the sound-absorbing material does not reach into the auricles or even into the ear canal of your horse.