I am sitting here recuperating from my dental implant...and a broken implant during the process! Dr. said he never had it happen before and not sure, but apparently side by the torx head broke while he was tightening it. All I know it was a 5x13, and he had to drill it out and was able to replace with a 6x13...and a bone graft. All the numbers don't mean a lot to me, except I believe the 13 is the length and 5 or 6, then, would be the diameter. Still in pain is all I know!!