From the Mueller web site: "The Ultra Adaptoid Plate is the result of a series of refinements to the original "Super Adaptoid Plate" and the "Super Adaptoid Plate MkII". The UAP has larger clamping blocks (2"), which give a better grip on the dovetail and are 9-5/8" center to center. The 1200 UAP (right) uses larger knobs to secure the (potentially) greater load that the AP 1200 mount will carry. The number of mounting holes has been reduced to 6 on the UAP 1200 and 4 on the UAP 900 (left). Both the UAP900 and the UAP1200 are 14" long."
$75.00 shipped MO or PayPal.