The VT-115A is known more commonly in the UK as the 6L6G is a larger more powerful audio beam tetrode than the 6V6 receiver type. This was used for audio amplifiers and modulators for small Amplitude Modulated transmitters.
The internally coated envelope obscures most of the internal structure. The base shows that the valve was made in the USA.
The top mica components showing the copper control grid supports and the U shaped grid cooling radiator.
The classic envelope has a maximum diameter of 51 mm and excluding the IO base pins the valve is 118 mm long.
References: 1040. Type VT-115A was first introduced in 1936.