This mask distinguishes itself from the known welding masks as follows: (a) by the window, which is round; (b) by the helmet, which is lighter and better insulating. The window consists of three of 120 o segments, among which the highest serves of viewfinder. The two others, angularly movable, have different colors appropriated to the light of welding (the one until 150 A, while the other for more than 150 A).