NcSTAR AR10 Upper Receiver Block Shooting Rests And Benches UTG ACCU SYNC 1 inch High UTG ACCU SYNC 1 inch High Profile 50mm Offset Scope Ring Mount for a Precise Fit on MIL STD 1913 Picatinny Rails Long term stability against UV degradation coupled with high impact and chemical resistant meaning these lamps will not yellow 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 This fully supports the inside and the bottom of the AR10 receiver and it also leaves the receiver optics rail open for mounting accessories and optics