There is already an abundance of information here in these forums regarding your question. But in answer, yes it will serve as a direct replacement in most PR based flashlights and lanterns. Anything from 3 to 9 volt will power it (maybe even a one cell). The thing to watch for is polarity. Not all flashlights and lanterns have the proper polarity. The tip MUST be positive, and the base MUST be negative. If the polarity is wrong, it appears you can kiss your EverLED goodbye. About the only restrictions other than the flexible voltage, and the absolute essential polarity, is the physical dimensions. The Princeton Tec TEC20 and TEC40 apparently doesn't have sufficient clearance in the head, and it bumps the lens.