1/2" Copper Tube Size Tube Clips Contains A Conveniently Pre-Loaded Nail In The Pipe Clip Which Will Not Pull Out Of Wood. They Are Used To Absorb Vibrations, Keeping The Pipe Quiet. The Nail Will Not Be Damaged If Overdriven And Can Be Installed In Alternating Directions To Ensure Secure Piping. Can Snap On To Any Cts Pipe.