The initial scope was designed around this 120 lb. 24" Zerodur mirror. To offset its massive weight at the bottom of the tube assembly, the head end box was built of substantial Baltic Birch and mahogany. When the 24" was replaced with a conventional 25" mirror weighing only 75 lb. it was too late to redesign and build a lighter overall design, so the resulting scope is considerably heavier than it would have been had we been able to start the design based on the lighter 25" mirror.