For me I thought these are nuts and bolt. It may look like one but its has a different name called
toggle pads. Used for clamping and positioning uneven or off-angle surfaces these metal parts are purposedly made for. It can be self-aligning and self leveling to eliminates clamp slippage if a force is applied. If you are looking for one find a black oxide finishor stainless steel quality material as it does not easily corrode or gets rusty.
