Replacement Knife 4.0mm Tip for the WLIR30 Weller Soldering Iron. The tip is easy to replace and is perfect for your electronic soldering tasks. Solder skillfully and confidently with Weller's 30W Soldering Iron with LED Halo Ring. With its 360 degree illumination, ergonomic molded pencil grip handle, easy-to-change tips, and integrated safety rest, it's the perfect high-quality and versatile soldering iron for all your soldering needs.