Tilta's 18" Threaded 19mm Rod is an 18" rod with female threading on both ends. This allows you to use optional threaded rod adapters to extend the length. As a standard practice Tilta chamfers one end of their rods and leaves the other end with a straight cut. The chamfering makes it easier to slide accessories on the rod, while the end with the straight cut makes for a smoother rod join.
The rod is made from machined aluminum for a balance between weight and strength and then anodized black for wear and corrosion resistance. Please note that there is no industry wide standard for support rod threading, so when sourcing optional rod extenders, it is best to stay within one brand.