While the tool from step 4 is used to tap a staple down flush with the bone surface, this specialized instrument is used to recess or "countersink" the staple bridge completely below the bone cortex. By placing the square, hollowed tip over the staple and tapping the metal end cap with a mallet, the surgeon buries the implant slightly into the bone. This is critical in areas with highly mobile tendons or minimal soft tissue coverage—such as the hand, wrist, or dorsal aspect of the foot—to prevent chronic hardware irritation and friction rub.