Birchwood Casey AR-15 Lower Receiver Vise Block - Birchwood Casey's AR-15 Lower Receiver Block installs to the upper receiver on standard ARs and equivalent firearms and allows users to torque the barrel down to the receiver. The magazine catch locks to the block, safely and securely holding the rifle. Clamps in any vise to make cleaning, assembly, disassembly, or repairs simple. Soft-jaw design prevents damage to the receiver.