Traditionally these would be used inside hanging lanterns. Smooth yet solid construction these lampholders give a "solid traditional quality look to any Lumiere they are fitted to. The cap of this lampholder has an internal locking screw to ensure secure fitting to the mounting thread.  The porcelain insert has all three terminals mounted to it allowing for ease of wiring.  Technicians will appreciate this time saving. When finally assembling be ready with a small slotted screwdriver to adjust the locking mechanism lug back out after screwing the skirt on to the base.