Vacuum Tube - 6SG7, Pentode, Semi Remote
New-Old-Stock (NOS) tube.
Also known by US military identifier VT-211.
The 6SG7 is a remote-cutoff pentode designed for use as a high-gain radio or intermediate-frequency amplifier. Features of the tube include high transconductance, low grid-plate capacitance, and a dual cathode connection to reduce undesired coupling between cathode circuits.