RAF Altimeter 6TM/9

We are not entirely sure of the background to this instrument although the data plate on the reverse confirms it was made by Kollsman Instruments Ltd of Southampton. It also details Ref no 6TM/9 and 'Altimeter Synchrohotel'. On the side wall of the case is painted 'Barschle Adjusted 29.01.80'. The crisp dial is graduated in 1000 of feet with a subsidiary readout showing actual height. It also carries a further label confirming it has at some stage been repaired by Kollsman Instruments at The Airport, Southampton. Apologies for the vague description but we are sure the experts out there will know exactly what it is! Dial width 3.25" (8.5 cm)