Battery for EWORK 20V/21V Max series cordless power tools High-density lithium-ion battery has passed 800 charge and discharge tests and still retains 80% of its capacity Built-in protection system to avoid overcurrent and overcharging, effectively extending the use time 12 Months & Support: EWORK Battery comes with a 12-month guarantee and 24/7 customer service. During this period, we will resolve any issues related to the product, installation, or usage for you EWORK 3.0Ah Lithium-Ion Battery for 20V/21V Max Series Cordless Power Tools - EK-3.0Y