Outback intake cover bolt

[outback650]

Can anyone ID this bolt that fell out of my intake manifold cover?
8mm and 5/16 are too small, 10mm is too big.
Is it a plastic speed nut?
2014 Outback 2.5 CI.
Thanks

 

[bmart]

8mm and 10mm heads or threads? Metric bolts are M6 M8 M10 etc. regardless of head/cap size.

 

[outback650]

Thread size. It actually measures out to a 9mm diameter.
My tire shop rotated my tires, apparently tried to check my engine air filter in the wrong place, and lost this fastener.