Was wondering if anyone shelled out and used one of these. If so is it worth it? I couldn't find a picture of the top of the shell and if it had an attach point, so can they be used at the track?
Check this link, I think your number may be off a bit.Most good paper filters will pass particles in the 90 to 95 micron range, and some tested, as much as 300 microns. Sand is about 125 microns and a white blood cell approximately 25 microns. Scotts stainless filter catches items down to 35 microns "absolute", which is about 3 times better than most good paper or brass filters.
A micron is one thousandth of a millimeter. That's about .00003937 inches.
Safety wiring for racing might prove to be tricky though. The outer shell is rather thick, so it is likely you'll have no trouble. There is no ready to use tab however.