All-Rites Rockguard Arms are used on our own custom Rockguards as well as replacements for Rockguards on several different RV’s and Motor homes like Fleetwood, Winnebago, Forest River, Thor, Skyline, Monaco etc. They come in four different sizes: 12", 13", 14", and 15". This measurement is taken with the arm closed. They come with the brackets to attach.