Boxed Negretti & Zambra test gauges

Currently residing in the hall, having been spotted by Mrs P's magpie like eyes, this is a cased set of Negretti & Zambra master gauges. Built by a company noted as one of the world's leading instrument makers, I've come across their barographs before but not pressure gauges (which are, I suppose, a barograph's first cousin anyway).

These are complete in their original box, with clamp and key.

Case 7 1/2 x 6 x 2 1/2 inches
Face 3 1/4 inch diameter