What make and model is this measurement microphone (not B&K)?

[capslock]

I purchased this on ebay on a whim. It was sold as B&K but it was clear immediately that it is not. There is a Logo on the side that looks like a W and M woven into one. And a number "1220" on the opposite side. On the back side, there is a CE sign and what is probably a serial number, five digit unlike B&K.

Thanks

 

[bohrok2610]

Probably Norsonic 1220.
https://norsonic.asia/wp-content/uploads/2015/04/Norsonic-Microphones-Datasheet.pdf

 

[capslock]

Thanks. Didn't know the logo, but that is it. Interestingly, in that data sheet, all mics look like B&Ks with the slitted diffusor. This one has the 1220 number but looks quite different with all these round holes.

 

[1audio]

The grid on yours liooks like the front plate is insulated from the housing. If so it may enable electostatic calibration/performance verification of the mike. The grid resembles the grid on the Gefell mikes https://www.microtechgefell.de/messtechnik-alle