Used, some yellow stains (see photos) covered by saddle.
Standard Size -  21" Seat x 19" flap length
 
From the Ecogold site:
The #1 saddle pad built for cross-country. Improve your safety and the protection of your horse’s back with the Secure XC saddle pad. Ride confidently as the air-flow fabric quickly evaporates moisture and the non-slip surface keeps your saddle in place. No slipping, no sliding, even in the worst conditions!