Direct experiments confirm the mechanism of metal-oxide-semiconductor field effect transis tor (MOSFET) ultrafast switching during which the switching times do not exceed units of nanoseconds. It was experimentally established that, in contrast to the known nanosecond range switches that either close or break a circuit, a MOSFET in the ultrafast switching mode can perform both functions. Possible applications of the MOSFET ultrafast switching effect in circuits of pulse formers with nanosecond rise and fall times are considered and illustrated.