The first point-contact transistor consisted of a germanium crystal placed on a metal plate. The germanium was of n-type with a so-called p-type inversion layer. Pressing down on this crystal was a plastic wedge, which was kept in place by a modified paper clip. On this wedge a thin gold foil, cut in two halves with a razor blade, had been cemented. The slit was very important to be able to make this point-contact device to work.