The RAM-B-347U base consists of a 1" diameter rubber ball connected at right angles to a 2" x 1.7" square base. The base has four pre-drilled holes at each corner, making the universal 1.5 x 1.188 (hole spacing) AMPS hole pattern.
Note: This does not include mounting hardware.
Like all the RAM products this is a quality product. Well made with a good quality finish.
This holder was a perfect fit for the Garmin Aera 660. For my particular setup, I used the Ram yoke mount and a 1 double socket arm. The Ram holder does not include any hardware, but this was not a big issue. I used metric hardware: Four socket head screws long enough to span the holder, the metal grommets included with the Aeras base, and the base itself - followed by locking nuts with nylon inserts. I used flat washers on both sides - socket head and locking nut. So far, this has worked exceptionally well and I have the Aera positioned exactly at the height and angle I like and with no vibration which were all issues for me with Garmins yoke mount.
Yes, this Ram Holder for Garmin Aera, part # 11-09853, has the same hole pattern that is on the Aera 660 Cradle.
This Ram holder for the Garmin Aera will fasten directly to the Aera 660. The Aera 660 will include a cradle with the same bolt pattern in the box, so if you are buying a new Aera 660, you do not need to also buy this cradle.