Redding's Titanium Nitride Neck Bushings are heat treated for durability and coated with Titanium Nitride to increase surface hardness and reduce sizing friction.
The bushings are available in sizes ranging from .185" to .368", in .001" increments, with the part number ending in the size (e.g., #RD76XXX).
This particular bushing has a diameter of .310 inches, fitting within the specified range of available sizes.