The Catkin version of the VMS4 variable μ screened tetrode dates from 1934. It was designed for RF and IF amplification in broadcast superhet receivers.
The printed information gives the Type designation. The sales brand would be indicated by a paper label - missing on this exhibit.
The bronze finish on the outer screen. The oval shape where the paper label was one placed is the right shape for the Osram consumer brand.
The screw top cap was common in the early 1930s. Punched into the screen are the words Patented and made in England.
The base pins, slit and compressed to bow out at the centre to grip the holder and make a positive connection.
The wide metal tube envelope is 33 mm in diameter and, excluding the B5 base pins, is 107 mm tall.
References: Data-sheet & 1005 Type VMS4 was first introduced in 1931.