The Tail Boot is an innovative Patent Pending approach to managing and growing long, beautiful tails. Made in the U.S.A with some recycled materials! Visit our "How to Apply" page to learn how to measure and apply. Sizing is based mostly off of thickness, however if you have a horse with an extremely long tail their sizing may be different. It is always best to measure and see what size would be best for your horse. Also, type in your horse's estimated height in the notes to seller box at checkout. For more product information visit tailboot.com.