Seidio Innocell 3500 mAh Extended Life Battery for HTC EVO 4G (Black) Seidio invests in extensive research to find the best and most powerful battery components on the market. We carefully select top quality Japanese cells for our batteries to ensure the highest level of safety, quality, and performance. Our research, knowledge, and expertise give us the ability to create batteries that provide maximum capacity in their comparable space. This large capacity Innocell Extended Life Battery is for the avid traveler who can't always get to a charger. Even with heavy phone and data usage, this battery will keep you charged and ready to go. In order to obtain the full capacity of your Seidio battery, we highly recommend that you leave the battery/your phone on the charger for an additional 2-3 hours after the charging indicator turns green or the battery status shows full.