Description from the vendor website:

Ruffwear Bark'n Boot™ Liners are socks for dogs that will enhance the fit, performance, and comfort of dog boots. The engineered knit and articulated shape match your pup's paw anatomy and minimize bulk, making putting boots on your dog a cinch. With moisture-wicking material and a tapered cuff, Bark'n Boot™ Liners dry quickly, provide comfort, and stay in place, even if your dog has a dew claw.

Size: 3/3.25in.