Naomi Wu 机械妖姬 on Twitter: "Little proof of concept I whipped up today. The 3M 603 + 501 + 5N11 combo is a low-cost reloadable N95 filter for elastomeric half respirators. This
603 - 3m - Filter Adapter, Mask, 6000 Series Full Face Mask
Filter Adaptor 603 16/box 3M | Whitebird
3M Respirator Filter Retainer for Respirator 5000 Series, Cartridges 6000 Series and Filter Adapter 603 (Case of 100) - 7100211073 - Ferguson