2n4921g.pdf datasheet:

2N4921, 2N4922, 2N49232N4923 is a Preferred DeviceMedium-Power PlasticNPN Silicon TransistorsThese high-performance plastic devices are designed for drivercircuits, switching, and amplifier applications.Featureshttp://onsemi.com Low Saturation Voltage - VCE(sat) = 0.6 Vdc (Max) @ IC = 1.0 A1.0 AMPERE Excellent Power Dissipation Due to Thermopad Construction -PD = 30 W @ TC = 25_CGENERAL PURPOSE Excellent Safe Operating AreaPOWER TRANSISTORS Gain Specified to IC = 1.0 A40-80 VOLTS, 30 WATTS Complement to PNP 2N4918, 2N4919, 2N4920 Pb-Free Packages are Available*MAXIMUM RATINGSRating Symbol Value Unit Collector-Emitter Voltage 2N4921 VCEO 40 VdcTO-2252N4922 60 CASE 772N4923 80