The MH-33 Battery Charger is designed specifically to charge EN-EL18d, EN-EL18c and EN-EL18b rechargeable Lithium-ion batteries. The MH-33 connects to the EH-7P charging AC Adapter which plugs into a wall outlet. The MH-33 can perform calibration of the batteries; and can fully charge an exhausted EN-EL18d battery in about four hours. The MH-33 battery charger cannot be used to charge EN-EL18 or EN-EL18a batteries.