All batteries have my name scratched onto them as we're used on site. All are tested and working upon sending. These batteries are the 18v Stanley system and are not compatible with the new V20 system The Stanley FATMAX 18V FMC688L 4ah 18V Lithium Battery is a reliable and powerful tool accessory for DIY enthusiasts. With a high capacity of 4 Ah and a voltage of 18 V, this yellow battery provides long-lasting power for a variety of power tools. The lithium-ion technology ensures efficient and consistent performance, making it a great choice for any workshop or home improvement project.