The Pro-Shot cleaning rod comes with a unique Proprietary Rod handle design. This unique design enables the rod to spin within the handle, making it possible for the bore brush to spiral alongside the rifling, thus ensuring a comprehensive groove cleaning. The cleaning rod is compatible with 27 Cal firearms and above. Please note that the #AD2 Brass Adapter provided with this product isn\'t intended to be a thread adapter. The purpose of the #AD2 is to facilitate a seamless transition for the .27/U diameter rods to accommodate accessories of smaller diameters like the bore brush or patch holder.