Need a little help with the Edgun Matador R5M

So I lost the ball bearing in the fill probe dust cap and am having a hard time finding the right one, Ed sent me the parts list for all his guns but all I could find in the parts list for ball bearings is 03 and 04 which doesn't make sense when you search for it.

I ordered 1/8 and 5/32 ball bearings because searching for 0.3 and 0.4 came up these sizes both are too big.



Any help would be appreciated.