1000Pcs 5N11 Gas Mask Filters Cotton Filters Cartridge Respirator Replacement. Approved for environments containing certain non-oil based particles. Function: Resist Non-Oily Particles. Material: High Electrostatic Filter Material. Particulate Cotton Filter: 10.4x 8.3cm. 1000Pcs(500Pairs) x 5N11 Cotton Filters. An unpaid case will be filled after 4 days. We will not be responsible for item loss due to wrong or unknown address. We promise to offer the lowest price and high quality produce. Welcome to our store! Your satisfaction is our top goal, we appreciate your business. To 6:00 p. Thanks for your patronizing!