In 1971 Telectronics commenced testing samples of a new type of energy source for pacemakers, the lithium cell (lithium battery) being developed by Wilson Greatbatch and in 1972 commenced development of a range of integrated circuits capable of operation from the 2.8 volts of the cell while providing a stimulating pulse of 4.5 volts. The combined technologies of a lithium cell, integrated circuits, hermetic titanium casing and an 0.5 millisecond pulse was first used clinically in 1974 in the model 120 pacemaker which was state of the art for that time. In 1981 a study of 28,669 Telectronics lithium powered implants showed a cumulative survival of 99.88% and a MTTF of 12,260 months. The longest surviving model 120 was electively explanted in 1993 after 17 years of operation.