I hadn't thought of that but TBH I was only thinking of a couple of metres. 3m would be enough to get to the other side of the rooms in my house; I think the only time I might need 5m would be if looking down a manhole.
It might not be hard to do but I wondered if they cut corners to keep costs down. Totally OT but each year we buy a new set of outdoor Christmas lights because they aren't as waterproof as they claim to be!
Interesting that some ebay sellers claim they can be used for ENT!