This is a chrome plated double nozzle used on the Hyper Gear, HTX, Mark III, and Optiplex. This is the "Slim" shape that is compatible with the nozzle adaptor part number M501S1 for the servo cutting heads.
Also known as L1383X, 36143311510, or 36143311511.
Double Nozzles have two chambers for the assist gas to flow through that changes the way the gas flows from the nozzle.
Chrome Plated nozzles are harder and last longer than the copper nozzles.