The M-21004 is a four-position advanced quad charger. Can fast charge all Frezzi NiCd, NiMH and Lithium-ion batteries as well as discharge and analyze them providing all information on a back lit alphanumeric display. Both units come standard with 4- NP-1 ports and 4- front BP-90 jacks. The M2100-4 offers 4 extra charger adapter cables of your choice. Both units offer a unique rescue mode for abused or over-discharged batteries and a 70W regulated power supply is included. Auto AC voltage select for worldwide operation is standard.