Packaged in a TO-3 case style, it is a 15 amp, 60 volt (or more, see below), 115 watt power transistor with a β (forward current gain) of 20 to 70 at a collector current of 4 A (this may be 100 to 200 when testing using a multimeter[6]). It often has a transition frequency of around 3.0 MHz and 6 MHz is typical for the 2N3055A; at this frequency the calculated current gain (beta) drops to 1, indicating the transistor can no longer provide useful amplification in common emitter configuration. The frequency at which gain begins to drop off may be much lower, see below.