These hollow drill bits are compatible with Euro standard paper drills. They are for drills with 2" (51mm) stack capacity. They fit European Standard paper drills by Babs, Citiborma, Concorde, Durselen, Foellmer, Hang, Kobold, Nagel, Nfpe, Marchetti, Mercury, OMM, Pescha, Stago, Uchida, Venus, and more.
Drill bit sizes up through 8mm have an 11mm shank. Drill bits 9mm and larger have a 16 mm shank.