Standoffs are threaded hollow Hex or Round fasteners that separate and position components while also fastening them together. The standoff hardware screws onto bolts or screws by hand. Also called standoff mounts, these fasteners are commonly used to raise one assembly above the other, such as elevating a circuit board above a surface. They can also be used to extend thread options or as an adapter to join male-threaded parts to female-threaded parts (and vice versa).
These are SS304 standoffs with 6mm male thread on one end, and 6mm female thread on another.