Made for a 25t chainring. This part hasn't had any real testing as of yet and was mostly made to protect my pants from chain grease. This part held up after 3 hammer strikes when I held it in a vice and failed after 4 so I'm pretty sure it would save a chain from hard impact but maybe only once :P . Design is heavily taken from a primo sprocket guard.

No

No

I would recommend a minimum of 5 perimeter walls for strength