Originally Posted by
WD40
No, there are 4 "thread-serts" or whatever you wish to call them that you use a rivet-gun to permanently affix to the large plastic cover on the Crossfire. So you are drilling the holes to accommodate the outside-diameter of the threaded-inserts, which then take a 4mm screw (also included with the Windstop). But the outside diameter of the threaded-inserts is 6.1mm. All this is specified in the installation instructions that come with the part.
If you wish I'll take pictures of it today.
No need for photos, but we are not talking of precision machining here.
6.0 mm = .236 diameter
6.1 mm = .240 diameter
A letter B drill is .238 diameter
A letter C drill is .242 diameter
There is not much difference between them.