Sadly the adaptor neither fitted my SW EQ6 tripod, nor the EQ6 mount head for my SW portable pillar / pier. But there is a solution – Please read on.
In both cases, the adaptor’s inability to accommodate the dowel used for mount azimuth adjustment is the problem.

Once the dowel has been removed, the adaptor performs otherwise as hoped, but its failure to fit an EQ6 head while the standard dowel remains in-situ is somewhat irritating.
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With the EQ6 tripod, the presence of the locknut at the base of the dowel prevented the adaptor being fitted.
In the case of the SW portable pillar / pier. there is no nut, but the dowel proved too wide for the groove in the adaptor and the groove was probably not deep enough either.
The adaptor would either need to be redesigned and modified accordingly, or the dowel can be removed, which seems ridiculous, since the adaptor has the appearance of being modified to accommodate a dowel, while failing to do so.

purchased adapter for my eq6 tripod/ioptron smart star cube mount, the tripod with the smart star is absolutely rubbish. The lock nut on the Azimuth post of the eq6 pod hinders the fit and the lock nut needs to be removed, a few turns of ptfe tape allowed the post to be refitted snuggly without the use of the locking nut.

Had to flair out the bottom of the cutout to accommodate the dowel locknut on my Skywatcher Eq6 - R mount so the adapter would sit flush on the base. Once I had done that the wedge fitted perfectly.

Does exactly what it is designed to do. I used mine to mount my Az Gti head on my spare EQ6 tripod that had been sat around for years. The tripod, while overkill for the mount head, totally transforms it and makes it more stable. The mount head is now defiinitely not top heavy and I use with confidence knowing something isn't going to topple over.

Got this item to fit on to an eq6 mount. However, my tripod's location stud has a locking nut which stopped the adapter from sitting flush (by about 3mm). Even removing the locking nut didn't work as the stud (by the way these are genuine parts) is too long to fit the cut out on the adapter. The only solution was to remove the location stud completely, which defeats the reason for the cut out to be there. - I can work with that without bothering to send it back.