Razertip heavy-duty #1 cord for Razertip burners and pens, one male connector on each end.. Also allows use of Razertip pens on other power supplies using an RCA connector. Example: Optima, Nibs. 1M (39") long. Standard "FL" cords (black plugs) use an 18-gauge cord for maximum flexibility. Heavy-Duty cords (red plugs) use a 16-gauge cord for maximum current flow, but it is not quite as flexible. For fastest tip heat recovery the heavy duty cord is recommended. Any of our pens work on either cord, but heavy duty and Feather Former pens/tips work best with heavy duty cords.