This package includes two genuine Makita 18V 4.0Ah LXT Lithium Batteries (BL1840) and one DC18SD 240V Charger. The BL1840 batteries offer up to 33% extra runtime and extended battery life, with the same size and weight as the 3.0Ah BL1830. They are compatible with your current Li-ion chargers and feature computer-controlled optimum charging. The batteries are also compatible with starred and yellow terminal machines. A cooling system maximizes battery life, and a built-in protection circuit prevents damage. LXT Lithium-Ion technology and the optimum charging system provide 280 percent total lifetime work with 2x more cycles. With a 5x lower self-discharge rate, the batteries remain active and ready for use, even after long storage periods. Charging at any time does not affect battery life. Built-in shock-absorbing features protect the batteries, and sixteen firm holding contact terminals reduce the risk of power loss during high vibration work. The battery's built-in Memory Chip communicates with the charger to maximize battery life using 3 Active Controls (Current, Voltage, Thermal). The battery is suitable for all Makita Li-ion LXT 18-volt machines.The DC18SD charger features a CPU that communicates with the battery's memory chip during charging, analyzing stored data to determine the optimal charging method, thus extending battery life. This charger is suitable for charging batteries up to 3.0Ah. Built-in sounds indicate charging status and completion. Makita's Forced Air Cooling Fan technology cools the battery during charging by forcing cool air through the battery's built-in air vents, prolonging its life.