The unique design of the Harlton's Mouth Wedge (side speculum) allows several teeth to rest on it at one time. This keeps it from slipping and spreads the force across several teeth to reduce the danger of cracking. The wedge portion is covered with a thick piece of polyurethane making it more comfortable for the horse. The polyurethane is durable and well accepted by the horse.
The length of the mouthpiece is 8.25cm (3¼") and is 3.8cm (1½") wide. The height (at the widest part) is 5.1cm (2") and the length of the handle is 21.6cm (8½"). The polyurethane replacement kit contains two polyurethane pads, eight screws and an allen-head wrench.