Protection from UV/IR
The degree of protection against infrared and ultraviolet radiation provided by the complete mask light filter.
Such protection is relevant primarily when working with electric welding: it is the electric arc that produces a large amount of IR and UV radiation. Exposure to these types of radiation on the skin can cause burns, and ultraviolet light is also harmful to the eyes. The degree of protection in this case is indicated in DIN units, and the larger the number in such a designation, the higher the degree of protection. In this case, 12 DIN is considered the minimum acceptable indicator, however, masks / goggles can be found on the market with higher protection rates — up to 16 DIN inclusive.
From a purely practical point of view, the higher this level of protection, the better; however, this characteristic significantly affects the price, and sometimes also the weight of the mask / goggles. So when choosing, it is worth considering the features of the planned work. For example, it is hardly worth specifically looking for a model for 15 – 16 DIN, if you have to cook rarely and little by little, but for professional use and large volumes of work, this level of protection will be very useful.
Filter class
Class is a complex indicator that determines the overall quality of the light filter in a chameleon mask (see "Type"). The class is indicated by 4 numbers, each of which describes a specific optical parameter. So, the first number indicates the overall clarity and lack of distortion; the second is the degree of light scattering; third — uniformity of blackout (presence/absence of visible blackout spots); the fourth is the angular dependence (how much the filter brightens when the angle of view deviates from the perpendicular). In each case, the larger the number, the worse this parameter is. The perfect indicator is considered to be 1/1/1/1, but in fact it is very difficult to achieve an perfect angular dependence, and there is no need to. Therefore, an indicator of 1/1/1/2 is considered quite sufficient even for a high-end professional filter.
Filter viewing area (WxH)
The size of the transparent part of the light filter — the "working window", the area through which the welder sees the place of work. A larger working window provides ease of use and a wide field of view, but it significantly affects the cost of the mask and somewhat reduces the strength of the light filter.
