Just a heads-up…the masks have an expiry date marked on the box…which is only a couple of months away.  Yes, there is an expiry date that Health Canada initially insisted to be on the masks. However, after further testing was done, at a much later date, it was determined that there was no deterioration or drop off in efficacy. Health Canada did release information on this very issue…

Click on the link below: 

https://www.canada.ca/en/health-canada/services/drugs-health-products/covid19-industry/medical-devices/personal-protective-equipment/medical masks-respirators/health-professionals.html#a32

Here is the relevant passage from the Health Canada website as above: "Use of medical masks beyond their shelf life....Medical masks can be used beyond their shelf life provided they have been kept in accordance with their labeled storage conditions and have not been used. Users should check that the straps are intact and there are no visible signs of damage. It is unknown how long after the expiry date the mask would be considered suitable for use.” 
Note also, Zentek contracted to a third party for further testing that was done 105 days after being manufactured, and it was found that exactly zero deterioration of the ZenGuard product (antimicrobial solution) or its' efficacy.