Transformer

Hilger & Watts
Transformer FF2-3
Made in England
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[divisional asset no.]
I.N. 2054
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[label on underside]
To change input:output tapping remove lower half of case (3 Amp Rating)

A Mains Transformer with variable output, probably used to illuminate the graticle in an Auto Collimator Microptic FF2-3 Hilger & Watts. The Collimator would be used to set up an item like a Head Up Display by providing a graticule aligned to a reference position and focussed at or near infinity.
The given width excludes its 1.7m mains cable.