If you own an 1100GTO-AE or 1100GTO-AEL, your mount has a double control box bracket to accommodate both of your GTOCP3 and GTOAE Control Boxes. You can continue to use the double bracket by mounting the GTOCP4 off-center and then securing it to the side.
Alternatively, you can purchase this single control box adapter, which attaches to your mount in the same manner. The GTOCP4 will look more aesthetically pleasing in this adapter.
Includes two 8-32 x 3/8" Thumbscrews.
Mounts used with this adapter: 1100GTO or any other mount that is bolted to a flat square plate.