Is this a 120?

I thought most jets had their "full" size stamped on it, eg 170 has 170 stamped on it, 35 has 35 and so on. This jet has 12 then a funny little logo, would this mean it is a 120 ? And if so would that be metric or imperial ? I assume 120 is 1.2mm but who knows

Thanks

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Is this a 120?