Apparently nobody has any real info, except possibly the same thought I had, that it's a late 60's, maybe early 70's vintage
Colortran fresnel, missing it's
lens.
I don't think you are going to find much info. especially on-line, as
Colortran has gone through many corporate upheavals in the past 40 years with most catalogs are MIA.
I would measure the diameter of the ring that holds what looks like the mounting clips for a
fresnel lens. If's it's 6", you could mount any
lens.
Note that the
socket with what appears to be an A lamp, is probably not original. I would guess that the
unit had a medium
pre-focus socket that used a 500
watt, T20 lamp
Would I put back a
MPF socket and 500
watt lamp ? - No, The condition of the wiring is such that I'd be hesitant to use anything over about 100 watts in the
fixture, noting that there is at least one
wire with a
ring terminal that is connected to nothing. It appears to be a green
wire which would indicate the
ground wire and should be attached to the
fixture chassis.
What do you desire to do with this
fixture ?.