Nickel Metal Hydride or NiMH batteries are considered "better" than NiCad batteries as they are less likely to exhibit the "memory" effect, have a higher storage capacity (+25%), and there is no toxic cadmium to dispose of when they finally wear out. NiMH batteries last an average 6,000 hours and can keep 80% of their charge at -20 degrees. You can use this device to recharge our Nickel Metal Hydride Rechargeable Batteries (47659-00, 47659-01, 47659-02, 47659-03).