The KTW63 is a beam or kink-less tetrode for HF and IF amplification in broadcast receivers and replaced the W63. The valve is variable mu designed to have the stage gain controlled by a voltage derived from the final rectified signal.
Note: The 6K7 family has pin 5 connected to the suppressor grid whereas the KTW63 has an internal connection to g3 and pin 5 has no connection. These valves are sensibly equivalent but not identical.
The reverse is plain. Under usual lighting the M-OV etched ellipse seen in the main image is not visible - only the Type designation.
The top screen leaves only the tops of the supports visible.
The classic envelope is 38 mm in diameter and, excluding the IO base pins the valve is 105 mm tall.
References: Data-sheet & 1040. Type KTW63 was first introduced in 1938. See also1938 adverts.