Yes, Pat is right.
They are unquestionably model 15s, or at least competent facsimiles, thereof. I will reference page 22 of Mergenthalers 1916 "Suggestions to Linotype Machinists"
These are very recent versions of a relic. Fluorescent lamps in the first posted photo suggest 1950s to 1960s. And those visilites are very new, again late 50s to 60s.
I am underthe impression that Mergenthaler produced Model 15s rather late, but through the 50s?