Size: #10 or 1/4" indicates the size of the screw

It is a socket cap screw, implying that it has a cylindrical head with a recessed socket for an Allen key (hex key) to tighten or loosen the screw.

The screw is made of A2 grade 304 stainless steel. A2 is a specific type of stainless steel, and 304 is a commonly used stainless steel alloy known for its corrosion resistance and durability.