If you are ordering a 10" ATS pier for your 1600GTO, you will need to order this adapter to interface the pier post with the base of your mount. You may also consider it if you are fabricating your own pier for either the 1600GTO or any 1200 mount. You do NOT need this adapter for the 10" Astro-Physics Piers.
This item is constructed of two machined aluminum parts bolted together - a thick flat plate and our Flat Surface Adapter for 1600GTO and 1200 Mounts (1612FSA). Since the bottom of the flat plate is designed to fit into the 10" ATS Piers, the diameter (9.450") is too small to be used in the Astro-Physics 10" Portable Piers. This adapter adds 2.015" to the height of the ATS pier.
The lower flat-plate section of this adapter is also drilled and tapped so that the 119FSA (formerly part # 900FSA) can be attached. This allows the 1100GTO and all 900 mounts to be attached to your 10" pier.