These anti-backlash motor couplers are designed for creating a decent join between stepper and servo motors and drive systems such as lead screws and ACME screws. They provide a good antibacklash platform that still offers a high level of precision.
 
The main body is made of 6061 grade Aluminium with a solid nylon anti-backlash knuckle for ultimate rigidity.  The grub screws provided with these couplers are made of high tensile steel.
 
Please note: 
These couplers may not suit some smaller build / hobbyist  CNC machines that have long, thin gantries and use V wheels for motion control. Upgrading to these couplers may increase vibrations and increase backlash due to the rigidity of the couplers. Please choose carefully before purchasing these couplers.