This is a new engine case saver or sometimes called a chain guide.  This guard helps keep the chain from flying through the engine when it comes off while ridding.    This case saver fits the ATC 350X 1985-1986.   To all the arrogant eBay viewers who keep telling me this case saver looks like another model's case saver I say this to you.  I have a 1985 & 1986 ATC 350X & I have this saver on both. I did modify mine some to make sure my case will not get damages in the event of a chain derailment, but I'm not scared to work on things to improve their performance.  Free shipping is in the US only. Thanks