ZWO AM7 with Pier Mount 90The Ultimate Mount and Pier Combination Introducing the ZWO AM7 with the WIlliam Optics Pier Mount 90. The telescope mount and foundation that grows with you. The Pier Mount 90 perfectly compliments the AM7 with a Pier capacity of 90 KG Perfectly suited to using the AM7 to it's maximum 30 KG capacity. Why Choose the AM7 Harmonic Equatorial Mount 1. High capacity, two ways Carries up to 20 kg with no counterweight. Up to 30 kg with a counterweight. 2.