The MKP 4.0 Ah Power Source Kit is specially designed for use with 40V Max & 18V LXT products being used in continuous operation. The BL4040 is a 40V Max Li-ion XGT 4.0 Ah Battery, a new type of cell with increased water & drop impact resistance. Communication between the battery & charger, allows to read more detailed information on the battery usage history. The BL4040 communicates digitally between the battery & the tool & battery & the charger & is equipped with 4 LED battery fuel gauge with a check button & cooling system for maximum battery life. The DC40RA 40V Max Fast Charger is designed for charging Li-ion XGT batteries, equipped with raised & enlarged charging indicator status light for a more visible indication, selectable melody sound for notification of fully charged battery & has two cooling fans, one for the battery & one for the charging circuit. The DC40RA is capable of performing consecutive fast charges of batteries & is compatible with the Makita Interchangeable Adapter ADP10 for charging Makita Li-ion LXT slide type batteries. DC40RA is wall mountable. The ADP10 Interchangeable Adapter Set has been designed especially for use with the Makita DC40RA 40 Max XGT Fast Charger to charge Makita LXT slide type batteries. The charging performance of the DC40RA Fast Charger with the ADP10 Interchangeable Adapter Set is equal to that of the Makita DC18RC & DC18RD chargers. The light on the DC40RA indicates the charging status. Charging times are Approx. 15 minutes for 1.3 Ah & 1.5 Ah, 24 minutes for 2.0 Ah, 22 minutes for 3.0 Ah, 29 minutes for 4.0 Ah & 40 minutes for 5.0 Ah & 6.0 Ah.