taken from modelsport site mate
*Unlock the 100+mph speed only with the Traxxas Link App and with optional #2872 5000mah 11.1v 3-Cell LiPo Power Cell LiPo batteries. Included high-speed gearing and High Downforce splitter are required for 100+mph operation.
**Unlocking 100+mph speed capability requires the Traxxas Link Application (download from the App Store) and an iPhone (4S, 5, 5C, 5S), iPod touch (5th generation and later versions), iPad (3rd generation and later versions), or iPad mini (sold separately). iPhone and iPod touch are trademarks of Apple Inc., registered in the U.S. and other countries