This is a 14 tooth pulley. It works with any 9 mm wide 5 mm pitch HTD belt. This pulley has a 3/8 in. hex bore making it easy to use on our 3/8 in. hex shaft or Robits Hex Shafts. This pulley comes as two identical halves that mesh with each other to create one pulley that is the correct width for a 9 mm timing belt.