Summary

This is a gas mask adapter - https://www.draegershop.co.uk/draegeruk/en/GBP/Products/Respiratory-Protection/Respiratory-Masks/Full-Face-Masks/Plug-in-filter-adapter-P-RA/p/6736770 .
Printed and tested. Everything fits right, just like the original from the link above.

Note: Not tested in high temperatures, when firefighting.

Print Settings

Printer Brand:

Creality

                                            <p class="detail-setting printer"><strong>Printer: </strong>                     <div><p>Ender-5 Plus</p></div></p>                                                                                <p class="detail-setting rafts"><strong>Rafts: </strong>                     <div><p>No</p></div></p>                                                                                <p class="detail-setting supports"><strong>Supports: </strong>                     <div><p>Yes</p></div></p>                                                                                <p class="detail-setting resolution"><strong>Resolution: </strong>                     <div><p>0.2</p></div></p>                                                                                <p class="detail-setting infill"><strong>Infill: </strong>                     <div><p>10</p></div></p>                                                    <strong>Filament:</strong> 3D Line PLA                Orange                    <br>                        <p class="detail-setting notes"><strong>Notes: </strong>                    </p><div><p>Printed with tree supports, with the smaller diameter on the bottom and the bigger hole with the thread on top.</p></div>

Post-Printing

Plug-in filter adapter P-RA