A combination of rigidity and easy assembly/disassembly makes these fittings popular for making chairs, beds, cabinets and more! They fit on the ends of narrow timber for a wide variety of applications. Screws engage through the keyholes and ride up the ramps under pressure, providing powerful wedge-tightening. We offer these steel plates in one hole, two hole, and one hole heavy duty versions. We've been selling these for over 50 years!