Major issue solved! When the common occurrence of the upper timing chain guide bolt shearing off in the cylinder head happens to you.... this is your fix! No drilling. No tapping. No metal shavings in your motor.  And most importantly, NO CYLINDER HEAD REMOVAL!!! Use in place of the guide bolt access plug as a permanent fix to the weak OE bolt.  Comes with instructions for installation.  Even if yours is not broken, strongly consider replacing this before it does break, the timing chain lets loose and valves get bent!!!! Here is a link to the youtube video about this product!  https://youtu.be/fpSSyXYw1Y4