Razor MX350 Dirt Rocket Versions 33 and Up W15120040003 and Beiter DC Power PK1270 High Capacity SLA Batteries Model versions can be determined based on the product ID code on your Razor product. The MX350 Versions 33+ 19 digit ID can be located on long white sticker on the battery /motor cover, back of charger, underside, and also on box W15120040003 Fully Charged Ready to Ride! Some Assembly Required