The CTC Corner Impaling Clip 4-Pack from Auralex is included as standard hardware with the M224 ProPanels. These clips are utilized to create a bass trap. The Corner Trap Clips measure roughly 4.5" by 6", and can be mounted to the wall or ceiling, and are removable. Use impaling clips alone for panels in low-traffic areas or when temporary mounting is necessary. Combine impaling clips and Tubetak Pro adhesive (purchased separately) when permanent mounting is required.