The AR15 Master Bench Block holds 5 key AR15 components in 8 different orientations to allow you to knock out and install up to 13 different pins. The block is wrapped in over-molding that grips your bench so it won€™t slide around. Clear, engraved labels tell you what component fits where, and what size punch you€™ll need to knock out the pins. The biggest innovation is mounted inside € four strong magnets immediately grasp any pin you punch out and hold it securely to the block. It even includes storage for common size pins. This is a bench block you can swear by.