Along with the Amcron/Crown IMA, a 'scope and a sig-gen, this was what we (now grey/no haired) used to use until the Sound Technology 1500A and the Amber 4400 stuff came along. (And then the AP or Neutrik stuff).
Paul Buff did a very good alternative to this, pertaining to his article in REP "Perceiving Console Noise and Distortion". (I think it was called).
The SHeiser thing is obviously European, because it has CCIR468 weighting filter, which was unheard of in USA at the time, or not used because it gave appalling noise figures compared to the dB(A) filter preferred there.