NcSTAR AR10 Upper Receiver Block Shooting Rests And Benches The integral design eliminates alignment The integral design eliminates alignment problems and the possibility of a loose connection between the base and ring UTG ACCU SYNC 1 inch High Profile 50mm Offset Scope Ring Mount for a Precise Fit on MIL STD 1913 Picatinny Rails Use just the lower half of the block by attaching it quickly to the AR10 upper receiver with the two provided receiver pins Bolting the two halves of the NcSTAR AR10 Upper Receiver Block fully supports the upper receiver to prevent damage from torque twisting forces when installing or removing barrels from the receiver