I know I've encountered these at least once before (possibly in the early 1980s at Cedar Point's Red Garter Saloon), and even written about them somewhere on here, but I can't find my own reference. [EDIT: maybe, maybe not: https://www.controlbooth.com/threads/brand-mfg-of-these-lights.26331/#post-236682 ] The way the lamp cap is attached is quite unique. Loosen the two knobs, then twist the cap 45° so the ears clear, then pull out. Med. prefocus socket. Has incandescent 500W DNS lamp installed. Pretty amazing that this light has both shutters AND an iris; no gobo slot though. I suspect the step lens is a 6x6, so would be roughly equiv. to a 360-6x12. Its most distinguishing characteristics are the large red knobs for focus and lamp cap. Anyone certain as to the manufacturer? @ship, do you have one?