The welding helmet mod. 421 can be used for all types of welding processes as of 5 amperes (MIG/MAG electrodes, TIG/WIG, plasmajet cutting and welding) except por laser and gas welding. It is specially recommended for TIG welding as it is equipped with a special detector for this kind of welding. The fastener system consists of a headgear with two straps (contour strap and cross strap). The circumference of the contour strap can be adjusted comfortably by turning the wing nut at the rear of the contour strap and the length of the cross strap can also be adjusted to seven dierent positions. The contour strap has two cushions that prevent discomfort at the points where the strap touches the wearers head.