The Jack Nut threaded insert is an economical blind fastener designed for assembly-line use in thin, soft or brittle materials. When tightened, the body collapses to form legs which grip the inside of the mounting surface, leaving a permanent, reusable threaded insert.It w ill not distort or deform soft plastics or thin sheet metal,not hole-size sensitive, and can be fastened securely despite burrs or uneven substrate.