McVitie Weston valve collection, Marconi-Osram Fleming 4-electrode valve
Marconi-Osram Fleming 4-electrode valve, marked 1, (RMW/H44 - McVitie Weston number), by M-O Valve Company Limited, 1923.
Marconi-Osram Fleming 4-electrode valve, marked 1, with special stand, (RMW/H44 - McVitie Weston number), by M-O Valve Company Limited, c. 1923.
Marconi-Osram Fleming 4-electrode valve, marked 1, (RMW/H44 - McVitie Weston number), by M-O Valve Company Limited, 1923.
Stand for Marconi-Osram Fleming 4-electrode valve, marked 1, (RMW/H44 - McVitie Weston number), by M-O Valve Company Limited, 1923.