Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4718558. I had a hard time finding STEP files for NATO gas mask threads, so I made some myself. These are for use in other designs, its not useful to print these by themselves. CC0 licensed, no attribution needed. You may need to scale the female connector x/y by 1.005 to fit some filters such as the Israeli M80. Test using the STL marked section. Connector specifications obtained from the [CDC](https://www.cdc.gov/niosh/npptl/resources/pressrel/letters/pdfs/FIGURE1-C-D_CBRNREV3_%20April2007_P3of3-508.pdf). [GOST version available here.](https://www.thingiverse.com/thing:4902291)