CMI Autococker Barrel Bore Sizing Adapters - 4 Adapters .685, .688, .691, .694 Change the bore size of your barrel in just seconds by adding one of five barrel sizers that come with this set. Its easy as one, two, three. 1) Remove barrel from marker. 2) Screw appropriate barrel bore sizer onto marker. 3) Replace barrel. Set comes with: .685, .688, .691, .694 Picture of adapters do not show 98 threads. You will recieve 98 threads.