【COMPATIBLE AIR PURIFIER MODELS】:Improvedhand Blue Pure 311 auto air purifier filter replacement is only compatible with Blue Pure 311 AUTO Air Purifier.NOTE: This is not OEM product. Any use of the brand name or model designation for this product is made for purposes of demonstrating compatibility 【SUPER CRAFT】Improvedhand 311 auto air purifier filter replacement ( ①Middle Main Filter ②Activated Carbon Filter with ARC Formula) is composed of true grate high-efficiency materials and powerful activated carbon. superior and mature manufacturing processes ensure that the filter maintains consistently efficient and stable performance throughout its operational lifespan.Every filter undergoes factory inspection to ensure reliable performance 【MAIN FILTER】:311 auto filter for blue pure air purifier was made of true great high-efficiency materials. Manufactured through the precision weaving and curing of micron-level fibers, incorporating both primary and supporting fibers.It involves precision weaving and curing of primary and support fibers using micron-level fibers, followed by machine compression into a dense waveform. This high-density, low-wind-resistance structure capture almost all of airborne substance 【ACTIVATED CARBON FILTER】:The activated carbon pre-filter for blue pure air purifier filter is formed by sintering powdered coconut shell activated carbon, achieving an internal specific surface area of 500–1500 square meters per gram. Its weakly polar surface enables effective adsorption of Vocs from the air and reduces smells from smoking, cooking and pets 【WHY CHOOSE US】:Improvedhand is committed to delivering high-quality products and exceptional service experiences to every customer. If you have any questions about our products, please feel free to contact us, we are always ready to answer your questions and solve your problem Blue Pure 311 AUTO Filter Replacement for Blue Pure 311 AUTO Air Purifier, Great High-Efficiency Materials With Activated Carbon Filter, 2 Pack, By Improvedhand