The choice depends on the breed, proportions (shoulder height, back length, weight), and your planned area of use. The best way to find the ideal model is to take our model selection quiz. Here is a brief overview: The MountainRock is robust and versatile, ideal for proportionally built dogs. The PeakStone is light and airy, with special versions for dachshunds and bulldogs. The ROOFPACKER offers maximum stability for dogs that need a very secure environment.