New-Old-Stock (NOS) tube.

Ther 12DQ6B is a beam power pentode primarily designed for use as the horizontal-deflection amplifier in television receivers. Its high zero-bias plate current at low plate and screen voltages makes the tube well-suited for use in receivers that operate at low plate-supply voltages. Except for heater ratings and heater warm-up time, ther 12DQ6B is identical to the 6DQ6B.