This twin pack of Makita 18v LXT Star Batteries includes 1 x BL1860 6.0Ah and 1 x BL1850 5.0Ah Batteries. Features and Benefits: Provides longer work time for increased performance and productivity. Charging takes 55 minutes when using the Makita rapid charger with the added convenience of an LED charge level indicator. The batteries have the same weight and size as the 5.0Ah, 4.0Ah and 3.0Ah batteries. STAR Protection Computer Controls protect against Overloading, Over-Discharging and Over-heating. Features include low self-discharge and energy storage capacity for long run times. STAR Protection is communication technology that allows the tool and battery to monitor conditions and exchange data in real time to protect against Overloading, Over-Discharging and Over-heating. Look for Makita tools and batteries with the STAR and get these protection features. OVERLOAD PROTECTION: High-drain applications require maximum battery power. Makita tools and batteries are engineered for industrial applications, but sustained peak demand can overload the tool. Makita's STAR Protection Computer Controls allow the battery and tool to communicate and protect your tool and battery from overload by cutting power when put under abnormally high current draw. OVER-DISCHARGE PROTECTION: Lithium-ion batteries are engineered for longer, sustained performance. But running a battery until it's "dead" empty can damage the cells. Makita STAR Protection Computer Controls monitor battery charge capacity, and if the battery is too low to complete the application it will cut power in order to extend battery life. OVER HEAT PROTECTION: Extreme heat is the enemy of ALL batteries. It can make batteries charge slower, damage battery cells, and reduce battery life. Makita STAR Protection Computer Controls help prevent overheating.