Review on Xnrtop Coupling Diameter Aluminum Connector Power Transmission Products and Couplings, Collars & Universal Joiners by Anthony Gupta

Specs say 5mm to 6mm. A 5mm hole is small (4.9mm). Motor shaft 5mm. Slight difference, but out of the bag it didn't fit the 5mm motor shaft. I didn't have a 5mm bit, but I did have a 5.12mm bit, so I used a power drill to enlarge the hole to 5.1mm. In this application of a telescope focus motor, too large a hole seems acceptable. what else can i say This is a well made clutch, the only downside is the small holes. If the holes were to specification then five stars.