This is a twin pack of the 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. 55 minutes when using the Makita rapid charger with the added convenience of an LED charge level indicator. Same weight and size as the 5.0Ah, 4.0Ah and 3.0Ah batteries. STAR Protection Computer Controls� Low self-discharge Energy storage capacity for long run times With overload, over discharge and overheating protection What are the benefits of the new "Star" 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 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