DL400 Offers a safe and secure method of transferring cables from a fixed point, such as from the door frame onto the door leaf. With a metal loop for better protection, DL400 has a minimum internal diameter of 10mm, which is sufficient to handle the most common cables used in door locking/control. The GFI is a concealed door loop, mounted in the hinge line of the door, it is completely hidden when the door is in the closed position.