This is a replacement soldering tip for the Weller Portasol Butane Soldering Iron Kit. The double-flat type tip is 1mm wide. Replacing the tip is a breeze — simply unscrew the currently attached tip with a flat-head screwdriver, slip the replacement tip in, and screw it into place.
The double-flat Weller tip has been pre-tinned with a lead-free alloy.