Transistors, invented at Bell Labs in 1947, gave engineers a powerful new tool for controlling the flow of electrons in circuits. Previous electronic devices used vacuum tubes that were fragile and consumed a lot of electricity. Transistors like these 2N337 units from 1957 proved far more reliable and needed very little power to function. The clear plastic block holds two examples of this silicon transistor design, one of which has the cover removed to show construction details. The 2N337 served as a high-speed switch for use in circuits on satellites.