The 6K7G is a screened pentode and was designed for intermediate frequency amplifiers in superhet receivers. It is high impedance type allowing for a high Q in the tuned anode circuit.
See also6K7 metal envelope version and 6K7GT glass tubular type.
Nothing on the reverse side.
The top screening plate. The cathode is round and the control grid connects to the top cap.
The classic envelope is 37 mm in diameter and, excluding the IO base pins the valve is 99 mm tall.
References: Data-sheet, 1040 & 1043. Type 6K7G was first introduced in 1936. See also1936 adverts.