You will need to order the Flat Surface Adapter with Flat Pier Plate for 1100GTO (119FSA-FP) made by Astro-Physics. The bottom portion of this part is made to fit directly into the ATS piers (1/8" wall thickness) without modification as per specifications provided by ATS.
* If you choose the 8" pier with 1/4" wall thickness, then ATS modification is required. Regardless of the wall thickness, the 119FSA-FP is sent to ATS to confirm fitting and will ship to you with the pier.
Allow 4-6 weeks for delivery