Thinline Ultra Trifecta Cotton Half Saddle Pad (medium, white) cotton, ultra thinline Made in US Back protection for both horse and rider. Shimmable for customized saddle fit Fits 17 and 17.5" saddles 21.75" spine length 16" across seat Sleek design fits under both off the rack and custom saddlesallowing for a close contact feel Superior Shock sbsorption reduces rider movement, clearing the way for closer, quieter communication. ThinLine's open cell technology provides 100% breathability and anon-slip saddle fit.