Electron microscope photo of the internal filter material of Zimi 9541 after use. Image from: https://www.reddit.com/user/zhouliang_mask/comments/1h5f6m0/electron_microscope_photo_of_the_internal_filter/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button
https://static.mstdn.science/media_attachments/files/113/613/557/710/099/108/original/fa2aa14a235ed428.jpg