These are your standard 9 Volt alkaline batteries from Rayovac. Don’t even think about trying to recharge these. Use them with Arduinos or with a voltage regulator to get a solid 5V for your project.
Check below for 9V connectors.
Note: This item is non-returnable. If this item arrives damaged or is not functioning properly, please do not hesitate to contact us to see if further actions may be taken.