Cleaning boiler tubes? That's just a wild guess.
Nope, I've cleaned several and even some chiller tubes. Trust me, I wish it was as simple as that tool looks.
I've seen one of those before, grandma ran a flea market and was a collector of all kinds of stuff. Looks almost like what we used to take milk sample with on the farm but ours was stainless. Maybe for an old style milk canister.
Not really sure though. I hope someone knows for sure. Interesting.
Patrick