This is a medium, barely-used hardness from Sleepypod in red and black. Sleepypod dog harnesses are the only harnesses for dogs that passed crash safety tests. For sizing and use instructions - see this video: https://www.youtube.com/watch?v=xBnDHBs6cCk&t=30s. My dog was an English staffordshire bull terrier, to give you an idea of the medium size. A new medium from Sleepypod currently costs 91.00 Canadian plus shipping.