Battery Type:Li-ion; Capacity:8.4Ah/94WH; Voltage:11.1V Replace Part Number:42T4899; Compatible Laptop Models: Lenovo ThinkPad X220 X220i X220S 29+ series Intelligent TI Chip and Circuit Protection Board Solution Guarantee Durable Usage and SafetyGood Performance A++ Cells Ensure Fast Charges and Low Power Consumption Our batteries are Intelligent control chip, durable A-grade battery to ensure maximum service life and power, save points and more. Built-in over-charge, over-discharge, over-voltage, over-current, over-heating and other multiple circuit protection, safe and stable. We are committed to providing every customer with high-quality batteries to keep your laptop running like new. If you have any questions or suggestions about our batteries, please email us. We welcome your comments and suggestions and are happy to assist you.