Cossor valve, type W.R.2., red painted spot on top of glass envelope, marked 309, (RMW/D4A - McVitie Weston number), by A C Cossor Limited, 1922.
Cossor valve, type W.R.2., red painted spot on top of glass envelope, marked 309, (RMW/D4A - McVitie Weston number), by A C Cossor Limited, 1922.