This is a twin pack of the Makita 18v LXT Star Batteries includes 1 x BL1850 5.0ah and 1 x BL1830 3.0ah Batteries. LXT Lithium-Ion battery and optimum charging system produces 280 percent total lifetime work with 2x more cycles. 5x Lower self-discharge keeps battery cells active and ready for use, even after long periods of storage. Charging at any time will have no effect on the battery. Built-in shock absorbing features protect the battery. Sixteen firm holding contact terminals reduce the risk of power loss/fluctuation in high vibration work environments. Battery's built-in Memory Chip communicates with the charger to maximize battery life using 3 Active Controls (Current, Voltage & Thermal). Battery suitable for all Makita li-ion LXT 18 volt machines. Star Protected Makita Battery The demanding applications you take on every day are also demanding on your cordless tools and batteries. You rely on your tools, so Makita created STAR Protection Computer Controls . STAR Protection is