Controlled atmosphere (vacuum or inert gas) induction furnaces, and power supplies therefor, as follows: a. Furnaces having all of the following characteristics: 1. Capable of operation at temperatures above 1123 K (850 °C); 2. Induction coils 600 mm or less in diameter; and 3. Designed for power inputs of 5 kW or more; b. Power supplies, with a specified output power of 5 kW or more, specially designed for furnaces specified in Item 1.B.4.a.