Replacement battery, compatible with: MX350 (version 33+)Pocket Mod (version 45+)RSF350 Razor Part #W15120040003 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.).