This exhibit is the three electron gun assembly from an early colour television tube. Each gun is identical and mounted firmly in glass rods to maintain their accurate equilateral triangle alignment.
Two of the guns seen side by side. The cathode is at the top with the various cylinders being for focus and acceleration. Deflection would be magnetic with coils arranged on the outside of the CRT neck.
The three central holes are where the three beams would emerge to converge on the holes in the shadow-mask and thence to the phosphor dots on the screen.
The glass foot. The brown substance is the cement that would have retained the base cap. In the centre is a copper tube.
The wide glass tube envelope is 50 mm in diameter, and including the base is 114 mm tall.
Updated October 28, 2015.