Yes please.You attach it to the chainstay with a rubber band using the curly braces, it holds the "feeler" (the rectangular piece inside the body) tight enough to allow you to push it against the side of the rim and true it. The little step at the end of the feeler also allows you to true it vertically.
It has saved a couple of friends on aour multi-day alpine rides so far.
If anyone is interested in printing one of these, let me know and I'll find a way to send the STL files.