Contact Mr. Porter directly. You can reach him via the AudiogoN emailer system. I have Porter Ports on all the lines going into my listening room. They are indeed very good. They hold onto heavy power cables like a pit bull on a pant leg.
I have found another improvement to add to them is replacing the cheap outlet covers with heavy brass. I have tried both polished brass and brushed nickel finish brass and find that brushed nickel sounds best with Mr. Porter's Pit Bull on a Pant Leg Power Ports
I have found another improvement to add to them is replacing the cheap outlet covers with heavy brass. I have tried both polished brass and brushed nickel finish brass and find that brushed nickel sounds best with Mr. Porter's Pit Bull on a Pant Leg Power Ports