Application
The helmets can effectively prevent infrared ray and ultraviolet ray fro transmittance and decrease incident light, thus preventing the worker's eyes from damage.
Dimensions
The filter plate shall beof such dimensions as to fit suitably into the frameand to cover the indow, to prevent leakage of radiations. The filter plate shall be not less than 2mm nor more than 3.8mm than 50mm ±0.8mm wide by 108mm±0.8mm long.
Optical Qualities-Cover Plates, Filter Plates, Safety Plates:
Both surfaces, waves, or other defects that would impair their optical quality. Plate surfaces shall be flat and substantially parallel; prismatic effects shall not exceed 1/8 prism diopte(approximately 4.3 minutes of angulardeviation). 
Transmittance
Filter plates shall conform with the radiant-energy transmittance requirements shown in Table 1 for Shades 4.0 through 14.0.