Add insane speed with power boosters when competing with friends! Build up to 4 different races with this versatile set! The stackable boosters are shaped like an arrow and they propel cars for awesome stunts. 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! Check out more ways to reconfigure and hack the track with the Builder's Guide (included). Level up with new track builds and experiment with items from around the house to make it epic! The possibilities are endless with open system play! Requires 4 D batteries. Not included.