Chemical Formula: W
WKL material is tungsten doped with ppm levels of potassium (K), aluminium (Al), silicon (Si) and is also produced principally as rod and wire. Compare with WKM, WKL wires have much longer longitudinal grain structure, which means much higher L/W value (grain length ratio grain width). According to produce processes, WKL wires find two main applications. One is as fluorescent lamp electrodes, which are coiled filaments because of its high coilability. The other is as halogen lamp filaments because its high temperature resistance.