Redding's 73 style steel neck bushings are heat treated and hand polished with a surface hardness of Rc 60-62 for easier sizing.
Bushings are available in sizes ranging from .185" through .368" in .001" increments, with the part number ending in the size (e.g., #RD73XXX for .263").
The specific product is a .263" diameter bushing, suitable for precision reloading applications in the neck-sizing process.