Large dog rear wheel chair by K9 Carts, lightly used, less than 1 month.  Everything is there pamphlets, leg straps, adjustment instuctions, allen wrench.

Dog Wheelchair for Back Legs – Rear Support – Large + Brace  this link provides details on how to measure.

Breed: German Shepherd Dog Age: 9 Weight: 78 Height: 26in Length: 23in Width: 9in Girth: 33in Sex: Female Strap Color: pink

all dimensions adjustable by +/- 2 inches.