The PV495 is a directly heated full wave rectifier. It was aimed at domestic radio sets and used the UK 4 volt heater. The balloon envelope suggests that this is from the early production around 1930 also the anodes are left bright whereas the later PV495 has blackened anodes and the later style of construction.
The central support rods hold the filament tension springs and via glass beads provide additional support for the anodes.
The dome carries the Tungsram name, Made in Hungary, Type designation and the words Barium Tube. The latter relates to the earlier Azide process of oxide coating the cathode.
The balloon envelope is 50 mm in diameter, and excluding the B4 base pins is 98 mm tall.
References: Data &1043. Type PV495 was first introduced in 1929. See also1929 adverts.