This exhibit is a Japanese version of the 6CW4. There is no maker's name on the can but the logo indicates a Hitachi product.
The 6CW4 Nuvistor was designed by RCA and is a triode for use at VHF and built into a small metal case. The base is ceramic sealed to the metal case and five fine pins, on a 12 pin grid, form the connections and the electrode supports internally.
The Nuvistor is built as a series of co-axial electrodes but they are all very small, and small inter electrode capacitances result. Thus the high frequency of operation. Unlike the transistors of the time the Nuvistor had the overload and intermodulation characteristics of the valve, superior to the transistor.
The maker's logo. See6BN6 for both logo and company name.
made in Japan.
The pins in the ceramic base.
The thin metal tube envelope is 10 mm in diameter and, excluding the fine base pins, is the 20 mm tall.
Reference: Data-sheet. Type 6CW4 was first introduced in 1960.