I used this to connect a shop vac to a grinder shroud that had 1-1/4 outlet. It worked okay except the 1-1/4" hose didn't fit snuggly inside the shroud outlet so I had to wrinkle it and force it in. Then, I put a couple wraps of duct tape on to hold it and that worked fine.
I thought it was a bit pricey but I needed it so didn't have a choice.