2-Pack of Lectron Pro 3.7 volt - 100mAh 20C Lipo Batteries for Estes Proto X / Syncro X Nano Quadcopter Lectron Pro batteries feature a high-end performance and reliability at an affordable price! Battery Voltage: 3.7V | Capacity: 100mAh | Maximum Continuous Discharge Rate: 20C (2 Amps) | Maximum Charge Rate: 2C (0.2 Amps) Battery Dimensions: 20mm x 14mm x 6mm / 0.79in x 0.55in x 0.24in | Weight: 2g Works great with Estes Proto X, Syncro X, and Hubsan Q4 Nano Quadcopter (Always check the voltage, dimensions, and battery connector to ensure this battery will be a good fit for your vehicle/application) We're confident in quality of our batteries! All Lectron Pro batteries are covered by a 1 Year Warranty against any manufacturing defects and U.S. based support in case you run into any issues!