Welcome to ANVOW. ANVOW Rechargeable AAAA Batteries for Surface Pen Active Stylus Pen. Any questions, we will respond to all your questions and try our best to solve the problems for you. ANVOW AAAA Ni-MH Batteries are perfect for a wide variety of household uses. Versatile Power For Your Household Electronics. Use them for everyday electronics such as alarm clocks, digital cameras, and universal remotes. Or for emergency supplies such as flashlights and portable radios. And don't forget playtime with wireless video game controllers, remote controlled cars, and other electronic toys. Item infos: Charger Type: Ni-MH/ Ni-CD battery charger Input DC 5V/200mA Output DC 1.5V/200mA Battery Type: Ni-MH Rechargeable times: Up to 1200 times Battery Size: AAAA Battery Capacity: 400mAh Package Includes: 1 x Smart charger 2 x AAAA batteries Note: In order to extend battery life, please charge the battery first before using it for the first time and before long-term storage. The batteries can only be used with device and charger with protective plates installed. The capacity of the battery is 400mAh, please charge it in low output current mode to prevent over-charge and over-heat. Battery comes with low power due to transport security, it may reach top performance after 3 cycles of full charge and discharge. We recommend using the battery at least once a month, long term idle may shorten battery's life. Store it in a clean, dry, cool place away from heat and metal objects.