The finish is black oxide and the length in the picture is 4.025" which is standard for the current C or D series blower. Be sure to measure the quill shaft or know what model blower you have when ordering.
RBS now also offers the PSI Extreme quill shaft which is a little larger in diameter and offers a little more strength for two stepping C rotor applications.
Stock diameter quill shaft is .630" in the center, extreme quill shaft is .780" in diameter.
Racer can choose which quill shaft from the drop down menu.