The construction consists of a neoprene or fabricharness clipped to an aluminum frame, which as attached to wheels positioned to replace the function of the rear legs. Because the wheels are interchangeable, the device can be used on dogs of different sizes or those in the process of growing. A knuckle mechanism allows the angle of the wheel to be changed based on the health of the animal, as well as allowing the device to fold flat. Walkin' Wheels also offers a front wheel attachment, which can convert the device from a 2- to a 4-wheel wheelchair.[citation needed]
