T Nuts

A T-nuts are also known as a blind nut, which can however also refer to a rivet nut or an insert nut, and it is a type of nut used to fasten a wood, particle, or composite materials workpiece, leaving a flush surface.
It has a long, thin body and a flange at one end, resembling a T in profile. The flanges of T-nuts often have hooks or serrations on the prongs that dig into a wooden workpiece as the bolt is tightened from the opposite side of the piece, providing better retention. T-slot nuts, which are used in work-holding in machine tools. T-slot nuts fit in T-section slots in the machine work-table and are used in conjunction with studs and clamps to provide flexible means of holding workpieces in place.