The VR27 (later named the CV1027) is an battery audio voltage amplifying triode. The VR indicates that this was specified and delivered to the RAF pre 1941 when the CV register came into force.
The old stores code of 10E/8239 is printed on the zinc screening paint.
The Air Ministry AM and Crown.
The dome carries the Cossor name, made in England, BVA and their code V10.
The balloon envelope is 41 mm in diameter and, excluding the B4 base pins, is 85 mm tall.
