The Birchwood specially designed block holds the upper receiver, lower receiver, bolt carrier group, front sight and charging handle for easy access to dowel pins for installation or disassembly. Soft jaw design won't scratch the receiver, solvent safe - won't fade, wear or crack when exposed to common gun cleaning chemicals, integrated magnet holds pins and small parts. Can be clamped in bench vise for easy access to receiver for assembly, cleaning or repair.