Nickel cadmium (NiCd) rechargeable. One of the earliest technologies for rechargeable batteries. Used for cordless power tools, personal stereos, portable telephones, lap-top computers, shavers, motorised toys etc, with a life of 4-5 years.  Using rechargeable batteries reduces the number of batteries requiring disposal, but 80% of them contain nickel cadmium, a known human carcinogen, and therefore need to be disposed of safely