It's a minipier, so it gets a mini-review. This minipier is all but impossible to find, but I managed to score one from OPT. I have been needing this for my setup so that I can comfortably do meridian flips without worrying about a tripod leg collision. Normally I would expect a piece of equipment like this to simply fit and not be a problem, but since this minipier has some important design flaws, I thought I'd post what I've found.
The first problem is that the raised rim on the outer edge of the top of the pier is thinner by 1-2 mm as compared to the raised rim on the tripod base. Therefore, the azimuth pin sticks up further into the mount cavity where the pin goes, enough that it hits the top of it and the mount cannot be put down flush onto the pier. My solution was to grind about 2mm off the top of the azimuth pin, but I was not pleased to have to do that. Another problem is that the 12mm center pin hole is too tight and I had to ream it out very slightly to get the pier to easily fit onto the tripod base. Finally, a minor annoyance is that the bolts that attach the pier to the tripod do not have the same hex wrench size as the az locking bolts (which use the wrench that comes with the mount).
After dealing with these issues, the pier does its one and only job of raising the mount 5.5 inches and now my meridian flips easily clear the tripod legs. However, iOptron really could have done a better job with this minipier.