WTS: Barrett adjustable rings. They are adjustable to 3.5 degrees and are extra tall. they have .9" between the mount and the bottom of the scope. Should mount on an AR or AR-10 and be tall enough and allow for the maximum adjustment of your scope. The have withstood my mcbros, my barrett, and a 7mm mag without moving. They are in very good condition.
You can see them on Barrett's website under accessories.