The 1083-POLOLU is a 6mm universal aluminum mounting hub allows you to mount custom wheels and mechanisms to motor shafts for 6mm diameter.
The hubs are sold in pairs, and each hub includes two 4-40 set screws for securing a motor shaft to the hub.
The set includes one Allen wrench and two 4-40 set screws for securing the hubs to motor shafts.
Each hub has four mounting holes for 4-40 screws (not included).