Set of 2 REAR wheels, compatible with:. Razor Crazy Cart Version 5+. Razor Crazy Cart Shift Version 1+. Razor Crazy Cart XL Version 3+. Note: Model versions can be determined based on the product ID code on your Razor product. The product ID code can be found on the battery cover and/or on the bottom of the frame.. The 7th and 8th numbers in your product ID code are the version number of your Razor product (e.g. ''01'' = Version 1, ''02'' = Version 2, etc.).