These equine dental speculums have an open frame, extending from one side of a horse's mouth to the other. Bite plates are positioned at the front to engage the upper & lower front teeth when the speculum is fully inserted. Two V-shaped sections extend to the rear from each side of the bite plates & act as wedges to engage the teeth & force the jaws apart. Simply, insertion requires placing the speculum frame around the horse's mouth, placing the V-shaped projections between the upper & lower front teeth & pushing until the upper & lower surfaces of the V-shaped sections open the jaws. Once fully inserted, the teeth are held in place by the plates to prevent the jaws from closing. Nose & head straps hold the speculum in place in the horse's mouth lowering the risk of injury to the user.