Metal shims are thin horseshoe-shaped plates for leveling up uneven structural steel on communication tower modifications. This allows for simple and quick installation and utilizes break away tabs which are broken off once the shim is tightened into position. AF tower metal shims are galvanized and stackable in 1/16 inch increments, making them easy to fit up. Stacking allows for larger gaps to be made level without a costly modification. Metal shims also see use in blind-bolting during structural upgrades on cell phone towers.