Vacuum Tube - 1LB4, Pentode, Power
New-Old-Stock (NOS) tube.
The 1LB4 is a low-voltage, low-current drain, battery type power pentode. It is designed for service with 90 volts of "B" battery and a single dry cell "A" battery. Its ratings and electrical characteristics are identical to those of the pentode section of the 1D8GT.