[Superscope]

Welcome to the Forum John,
and in particular, welcome to this corner of Avo inflicted Forum Members,
where the Avometer gets a regular airing.

Dave has pretty much said most of it.

You have a fairly early Model 9sx, from December 1963.
You didn't say if it is in working order or not?

The Model 9sx was the first Model 9 produced, so essentially it is the
defacto Model 9 Mk I.
It was the first to use the 0 - 30 Scale on a full sized Avometer, rather
than the 0 - 25 found on the then current Model 8.

They are not Rare Meters, although the 9sx labelled ones are less common.

They were made between 1961 and 1971, but there is evidence that they
might have still been leaving the Factory in small numbers as late as 1974.

It was later, simply known as the "Test Set Multirange No1" and the Model 9sx
monika was dropped although the Meter was largely the same device.

It was made especially for the British Military, and there hasn't been any
evidence seen so far to suggest if it was ever sold directly to the Civilian
Market when New.

The (Multimeter Type 12889)and 5QP/17447 are the earlier Military designations
before the "Nato Stock Numbers" NSN were introduced.
It later had the NSN 6625-99-105-7050
Originally, it would have come in an Olive Drabe Coloured Soft Vinyl Case.

It was replaced by the Military variant of the Model 8 Mk V in around 1972.

I still use a 9sx regularly.

Ian