The neoprene exterior works together with the inner UltraShock™ lining of the boot to provide 360° exterior leg protection against injuries caused by hits from hooves, debris, and other horses. As a general rule, horses will wear one size larger on the rear than on the front. However, in some cases where there is no pronounced size difference in the fetlocks, the horse can wear the same size in the front and the rear.
Small - (10-1/4"L x 10"W) Fits horses 14 to 15 hands high
Medium - (11"L x 12"W) Fits horses 15 to 16.2 hands high
Large - (11-3/4"L x 13-1/2"W) Fits horses 17.2 hands high.
These boots are a great price for a brand name that makes a hard wearing product. I will say that I like the newer style (like the elite and the ventech) boots better. But these are an old standby. I have a pair around most of time to help support my mares legs and protect them on a trail ride. And these will cover their legs up just as well as the expensive ones that's why I like them =)