The holes in question are the what I would call the "two" 10.5mm holes going thru both walls of the tube. See attachment. My experience has been these are denoted as 2X 10.5 THRU (OR THRU BOTH WALLS). I'm struggling with calling this 4X.
And what about the other "three" 12mm holes going thru...
Hole Callout...
Square tube with a hole going through the entire part (both walls). The hole(s) are being located using a positional tolerance and basic dimensions. In this example, is best practice to call out the hole as one thru hole or two holes? We've always called this out as one hole...
