It was developed by Sheldon J. Segal and Horacio Croxatto at the Population Council beginning in 1966, with the first clinical trial in Chile in 1974. It was first approved in Finland on November 23, 1983, where it was manufactured by Leiras Oy Pharmaceuticals. The original Norplant consisted of a set of six small (2.4 mm × 34 mm) silicone capsules, each filled with 36 mg of levonorgestrel implanted under the skin in the upper arm and effective for five years. The original (six-capsule) Norplant production has been phased out; USAID's contract ran until December 2006.