The piece of equipment is also called an endoscope. I have used them from time to time for surveying buildings - checking out cavity walls, spaces in service ducts, under floors etc.
The first endoscope I used was quite chunky. It had batteries mounted around a belt, like weights on a diving belt. The belt was so heavy that I felt decidedly shaky when climbing an extension ladder, wearing the belt, to inspect roof eaves. The model I used had an accessory for attaching a stills camera to photograph what was seen.
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