 Sprague Electric Company was one of the first companies to purchase a license agreement from Philco in late 1955 and started to manufacture the surface-barrier transistors under its Sprague name, in early 1956.Another company to purchase a license agreement from Philco in early 1957, was Semiconductors Limited, a division of the British-based Plessey Company.In 1959, General Transistor Corporation had also purchased a license agreement from Philco, to manufacture its complete line of high-speed transistors.