McVitie Weston valve collection, Tungsram valve, type GDG 4100
Tungsram valve, type GDG 4100, (RMW/G21 - McVitie Weston number), by Tungsram Electric Lamp Works (Gt. Britain) Ltd..
Tungsram valve, type GDG 4100, (RMW/G21 - McVitie Weston number), by Tungsram Electric Lamp Works (Gt. Britain) Ltd..