The Wal-Board Tools CO-2A 1-1/4 in. Corner Bead Tool With Mallet crimps the metal to attach 1-1/4 in. corner bead to drywall corners. It is made of durable aluminum with an all-steel crimping assembly. It quickly secures metal corner bead with a few strikes of the included rubber mallet and is also handy for straightening a bent or misaligned outside corner bead.