expanding metal wall anchors

A wafer head screw, as the name suggests, has a flat, thin, and circular head, resembling a wafer. The head is usually larger than the screw's body, providing a broad bearing surface that distributes the load evenly and reduces the chances of damage to the material being fastened. The self-tapping attribute refers to the screw's ability to cut its way through the material it is inserted into, forming threads as it goes, hence the term self-tapping.

...

In addition to their durability, stainless steel self-threading screws are also known for their strength and reliability. The unique thread design of these screws allows them to create a strong and secure hold in the material they are being driven into, ensuring that they will not come loose or fail over time
stainless
stainless steel self threading screws. This makes them a popular choice for applications where safety and stability are paramount, such as in the construction of buildings, bridges, and other structures.

...