Didn't fit on my freehub. Bit of googling revealed it's only compatible with a 12sp freehub.
Now that's a niche within a niche!
I was a bit cross about it as I wanted to finish my sscx refurb, but mainly I think it's funny and sums up the bike industry perfectly.
Edit: I'm an idiot!
Was trying to install it the wrong way round. Assumed it would be like a Surly cog with the flared part facing you.
This sums up the amateur bike mechanic perfectly
