Voltage Monitoring Function - AV Control, Auto Switch to Trickle Mode After Full Charge 2 Hour Rapid Charger Safety Timer, Auto Cut-off After 3 Hours of Standard Charging Charge 2 or 4 NiMh or NiCd Rechargeable Batteries. LED Indicates Charging Status Temperature Monitoring, Over-Heat Protection Bad Battery, Alkaline and Primary Battery Detection Supplied with 4 x 2100MAH Rechargeable Batteries Complete with 12V Car Adaptor