Finished bore sprockets are known as "Type B" or "Type BS" sprockets. These sprockets have a hub on one side with a keyway & 2 setscrews. One setscrew is position over the keyway and the second is 90° off the keyway. Our sprockets are manufactured from quality carbon steel and have the teeth hardened for wear resistance. All Nitro finished bore sprockets are made to the ANSI B29.1 industry standards for chain & sprockets.