The 8mm single pulley, assembled with a set screw, is used on all Ultimaker 2 series, Ultimaker 3 series, and Ultimaker S-Line printers. This is an official Ultimaker part for the following machines: Ultimaker 2+ Connect Ultimaker S3 Ultimaker S5...
 The 5mm pulley, assembled with a set screw, is used on all Ultimaker 2 series, Ultimaker 3 series, and Ultimaker S-Line printers. This is an official Ultimaker part for the following machines: UltiMaker S7 UltiMaker S5 Ultimaker S3 Ultimaker S5...