- PREMIUM QUALITY: Reusable 100% cotton fabric face masks are made of 2 layers of fabric with a pocket for the filter. Executive Standard: FZ/T 73049-2014. Each mask includes a pack of 2 filters. Executive Standard: GB/T 32610-2016. PM 2.5 Filters are 5 layers - 4 layers of non-woven fabric and 1 active carbon layer. Filters are single-use and best used within 2 years of mfg. Refills are available for purchase. Earloops are made from 55% nylon and 45% elastane, soft fabric.