This is a store returned (tried on, shows a little dirt on treads) Cavallo Trek horse boot ( single) in a size 5 Slim (5 9/16”-5 13/16" , width is 1/4" smaller on slim than the length).   

These boots are Breathable, tear proof and abrasion Resistant with a Honeycomb Design for optimal strength.

• Built-in sole relief takes pressure off sole, bars and frog 
• Moulded-in TPU back flap for maximum bulb protection  
• Maximum shock absorption 
• Reflective for safe riding