Tack

any of the various equipment and accessories worn by ponies. Saddles, stirrups, bridles, halters, reins, bits, harnesses, martingales, and breastplates are all forms of horse tack. In the case of the human pony, it may include all or part of the costume.

*taken from - The Human Pony: A Handbook for Owners, Trainers and Admirers found at http://www.greenerypress.com/