The optrel e684 is the perfect welding protection for joining aluminum, chrome-nickel alloys, special metals, and steel. With a continuous, infinitely adjustable protection level range from Shade Level SL 5 to SL 13, the e684 is suitable for all types of arc welding and cutting processes. Classification: 1/1/1/1. A faulty weld can sometimes be a matter of life and death. Therefore, having a perfect welding helmet is all the more important. It makes welding work safer, more efficient, more precise, and more comfortable. Only the best is good enough for this purpose. Don't settle for less. The e684 model is a loyal partner, especially in the fields of vehicle and rail vehicle construction, chemical, container, machine and plant engineering, pipeline construction, and shipbuilding. Less is not enough!.