The authentic version by Achille Castiglioni for Flos. Lamp is in excellent condition and is currently disassembled. Incandescent version.
taken from Flos website
"The Arco is a design icon that has been in constant production since its debut in 1962. The famed Castiglioni brothers spared no detail when they created it, from the beveled corners of its genuine Carrera marble base (designed not to hurt should you brush against them) to the strategic hole that allows for easy lifting of the base.
The base supports a spun aluminum reflector via a curved stainless steel adjustable stem, allowing the lamp to offer both direct and indirect light. The height extends to almost 7-feet, allowing for easy placement of a couch or table underneath."