DIYers and repair folks, these jack nuts (sometimes called petal nuts) are seriously handy for mounting things on hollow walls, thin metal, plastic, or polywood where regular anchors just won't work! You get 80 complete sets with M4 stainless steel expansion anchors and matching screws - plenty for multiple projects or repairs. The stainless steel construction means they won't rust or corrode, even in damp environments. Installation is surprisingly easy - just drill a hole, insert the jack nut, and as you tighten the screw, the anchor expands behind the material to create a super secure mounting point. They provide way more holding power than plastic anchors, especially in those frustrating hollow wall situations where you need something substantial to hold weight. The expansion design works great in materials that are too thin for traditional anchors, giving you a reliable thread that won't pull out easily. Perfect for mounting shelves, brackets, signs, or any fixture where you need a strong connection in challenging materials. The M4 size is versatile for most medium-duty applications around the house or workshop. Much better than those cheap plastic anchors that strip out or fail over time. Having 80 pieces means you can tackle several projects without running back to the hardware store. Essential for anyone who does regular mounting or repair work!