lower sprocket guard question

#1
I am wondering if anyone has a lower sprocket guard installed because it seems like a really smart idea to me but I can't find one the right size, I measured my sprocket and it's a 60 tooth measuring 10" across, where do I find a guard that big? The biggest I can find is 9". I've also seen sine Karts that have a metal arch running under the sprocket, is there anyone who sells these?
 
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