I'm gullible and it could be a scam, but FWIW and just in case. I got a virus warning purporting to be from Microsoft and Norton this morning advising not to open a powerpoint presentation: "Life is beautiful". (It is but not always on the net.)
*********************************************Tip: I found some self drilling sleeve anchors for concrete, hardened and about 7/16 in, diam. X 1 1/2 in. long. The toothed end closely resembles a small version of a Stebcenter. There is no center pin, but the thru hole at the toothed end is 1/4 in. and half way thru the other end is
5/16. both ends with standard female threads.Looks easy to make a small drive center to be held in a Jacobs chuck by adding a center pin and bolt with the head cut off. Or add a spring and center pin to make a 'Stebcenter'.
************************************* 2nd warning:I remember the brouhaha here about making a patented center marking device for square blanks, so _DO NOT_ [repeat, DON"T] sell these knockoffs.) :)
Turn to Safety, Arch Fortiter