The CellVault 21 Battery Storage Case provides secure storage and organization for your 21700 batteries and SL B50 compatible cells in a durable black housing.CellVault 21 Battery Storage SystemCompatible with 21700 lithium batteriesSL B50 battery compatibilityDurable black constructionModel: CV21001Essential for safely storing and organizing your rechargeable batteries keeping them protected and easily accessible for flashlights vaping devices and other electronic equipment.