It is a bit dusty but should clean up nicely.

Twin 50ohm trembler coils, so I connected it up with two AA batteries (3Vdc total) and it worked straight away with a nice bright ring tone, just as I remembered them!

The bell / metal parts are nickel plated and the black base is of Bakalite, not plastic.

Printed on the end of the base is ''Tropical Finish' indicating it had a special treatment so as to be unaffected by moisture and higher temperatures for Military application and foreign use.