The excavated brass staples with O-rings were designed by Chudnow and are made by Chiarugi. These have a #2 bore size. These vibrate significantly more responsively than the 'S' staples. To extend the life of your O-rings, it is recommended that you lubricate them with your reed-soaking water before inserting into the oboe. If you need replacement O-rings, they are available for the asking.
For extensive information on choosing oboe staples, read our Oboe Staples Guide, How to Select Your Oboe Staple