There are 2 products.
Thoriated red tungsten electrodes, used for welding steels and nickel alloys. Made for applying straight polarity or DC Electrode Negative (DCEN). Not recommended for AC welding due to risk of splitting electrode when maintaining balled end. Recommended for steel applications. Sold in packs of 10.
Zirconiated white tungsten electrodes, used for welding particularly high currents. Unlike thoriated tungsten electrodes, these electrodes can conserve a balled end and have a very stable arc when welding, resulting in less permeation and high resistance to corrosion and contamination. Recommended for aluminium applications. Sold in packs of 10.