Cool tool.

What you see in that vice is a conventional wrench that uncle Fester heated and bent into a crescent shape with the help of an oxy-acetylene torch.

(In the background is a lovely front wheel off a 1990s Harley-Davidson)

An obstruction spanner like this is needed if you want to tighten the two nuts on the Norton's cylinder head, the number 7 and 8 in the tightening sequence, without having to remove the exhaust pipes, a real bonus!

I have a small set of these on the way and they should arrive just in time to get the Norton ready for the road again; fingers crossed.