Tighten to bolt by hand. Add a second Tufnut, back to back. Tighten the two nuts together with a wrench. Remove the second nut, leaving the first nut tight and secure.
Use a wrench or special tool number T58 to tighten the nut. When the nut is tight, keep twisting firmly and the hex head breaks off, leaving the vandal proof tapered nut screws.