The 6AM4 UHF triode is designed for grounded grid operation to ensure the maximum isolation between input and output circuits. This example is a laboratory sample, probably supplied to a manufacture for them to design appropriate equipment.
The grid has many connections in order to approximate to a ring. The article on valves for bands III, IV & V gives details of the construction of the 6AM4 that builds a sensibly planar valve into a B9A envelope.
The gold-plated pins indicate professional usage in communications link equipment eg. on a microwave link tower. This is not your average TV valve! but it was originally designed as such.
The triode is mounted horizontally and the grid extends out past the anode. The anode is shaped to place a small flat section close to the grid but further out is extra metal to radiate away the generated heat.
The vertical mica sheets that hold the electrodes in place.
The thin glass tube envelope is 20 mm in diameter and, excluding the B9A base pins, is 37 mm tall.
References: Data-sheet & 1040 Type 6AM4 was first introduced in 1954.