Orion 9600 11 Pound Counterweight for Atlas Pro AZ/EQ-G Mount Extra 11-pound counterweight designed for the Orion Atlas AZ/EQ-G GoTo mount Helps balance especially heavy telescopes and instruments on the Atlas Pro AZ/EQ-G Ideal for balancing heavy astrophotography gear or heavy telescope optical tubes Features a nylon-tipped, tri-lobe lock knob for easy grip - even while wearing gloves in the field! 1" center bore fits Atlas Pro AZ/EQ-G, Counterweight Shaft Upgrade for Atlas EQ-G, Skywatcher AZ-EQ6, and other mounts with 1" counterweight shaft