Tektronix may be known best for their industry-leading oscilloscopes, but they also sell other test equipment, including a line of handheld multimeters in the 1990s.
The model documented here is a DMM912, part of a series of multimeters that included the 912, 914, and 916. All are RMS-responding, 4000/40,000-count models with a number of premium features like min/max/average, auto-hold, peak-hold, AC+DC, lead warning, and memory storage. The display updates 4/sec in 4000-count mode or 1/sec in 40,000-count mode. Accuracy and bandwidth increases with each model; this 912 is rated at 0.2% basic DC accuracy and a bandwidth of 1kHz. The 914 and 916 make use of a secondary numeric display for simultaneous ACV and Hz readings, the 912 does not.
The basic Beckman multimeter design that seems to apply to many of their 3½ digit models from the late 1970s onward include an LCD/processor chip assembly held together by various plastic parts that simply clip together. The later Wavetek-branded models in the 1990s changed the design slightly to use self-tapping screws to hold the stack together.
The first two generations of the popular 70-series Fluke handheld DMMs included the 21 and 23 models, which were the same as the 75 and 77 respectively, except their cases were safety yellow instead of the usual dark gray. The third generation of the 70-series also included the 21-III and 23-III models as well, but they look exactly the same as their 7x-III counterparts. It is my understanding that the only difference was that the 2x-III models were packaged with premium test leads. Just marketing, I suppose.
The HD140 digital multimeter from Beckman Industrial is another in the “heavy-duty” series, very similar to the HD110 in a 
The HP 3468A multimeter 