Stores ref. 5D/551. By Sperryn. Type A. Vitreous enamel base with brass domed top and single toggle double pole switch. 5 Amp, 250Volt. The reference refers to 'Aircraft Armament Electrical Items'. Probably used on pre-war and early war aircraft. There are a few minor dents and scratches on the dome, otherwise in very good used condition. Lovely clear Air Ministry and King's crown markings. Stock code M21322.