The PV495 is a directly heated full wave rectifier. It was aimed at domestic radio sets and used the UK 4 volt heater. The same type of rectifier was made by many European companies.
This later version was Made in England. We also have an example of the early construction of the PV495 that was made by the parent company in Hungary.
The anode construction of a round ended channel with a side fixing flange was common practice.
The oxide coated ribbon filament can be seen through the top mica. The hooks holding the filament form the tension springs.
The etched lettering on the dome includes the filament voltage and the anode voltage of 2 x 300 Volts.
The classic envelope is 44 mm in diameter, and excluding the B4 base pins is 103 mm tall.
References: Data & 1043. Type PV495 was first introduced in 1929. See also1929 adverts.