Hebei Nuo'an Technology Co,.Ltd is a Chinese company that manufactures toxic gas filter boxes and canisters. They provide contact information for Snowden Dong and details on their NA-GM-40 and NA-GM-41 product models. The filters are made of coated aluminum and pleated glass fiber paper with activated carbon and have a particle efficiency over 99.995% and dimensions of 110*92mm. They can filter organic, inorganic, acid gases and vapors as well as solid and liquid particles and are intended for gas mask filter replacement with a minimum one hour service time.