Hot Wheels Track Builder System Power Booster Kit is another great set to build many possibilities of open system play! The Power Booster Kit includes 35+ pieces including 2 speed loops and 2 boosters so you can boost your crash, your loops and head-to-head races! Not only that, you can convert the packaging and other household items into another epic track! How cool is that! This is suitable for aged 5 and above. It requires 4 size D batteries to run the boosters which are not included.