These appear to be un-rated.
To those outside of the healthcare arena there are 2 basic facemask standards in the United States:
SURGICAL FACEMASKS are designed for use by healthcare personnel (although obviously they can be used in something like the current COVID-19 pandemic) mainly to PREVENT THE MASK USER from spreading microbes TO A PATIENT (such as in the operating room). These standards are maintained by the ASTM (American Society for Testing and Materials, now ASTM International), and are rated from 1 (least resistant to failure) to level 3 (highest resistance to failure). Usually, reading the standards requires a subscription to the ASTM, however during the COVID-19 pandemic they are available publicly. See: https://www.astm.org/standardization-news/?q=features/standards-medical-face-masks-and-protective-clothing-.html. Notice, it COSTS MONEY to test & certify a mask.
In order to filter air FOR THE USER, such as when breathing air contaminated with small particles such as metal, plastic, or unhealthy particles which might get into the user’s lungs (such as COVID-19 virus particles), NIOSH (National Institute for Occupational Safety and Health) has a standard called N95 (filters at least 95% of airborne particles), all the way up to N100 (filters at least 99.97% of airborne particles). See: https://www.cdc.gov/niosh/npptl/topics/respirators/disp_part/default.html
These, too, require testing and approval by NIOSH to allow certification.
Up until recently, you could purchase these in any Walmart or Home Depot (to be used such as when sanding-off lead-containing paint, sandblasting, etc…), but of course supply and demand stresses have caused these to disappear.
Notice that the N95 standard is meant ONLY to prevent particles coming INTO the user’s lungs and does NOT concern itself with a contaminated user EXHALING particles (such as viruses) OUT into the atmosphere (or into someone else’s face). Because of this, N95 compliant masks CAN have devices such as valves that allow unfiltered air from the wearer to leak into the environment. In other words, for someone who is SHEDDING virus, they can still SPREAD VIRUS TO OTHERS if a mask containing one of these valves is present. Obviously, you can’t use these in the Operating Room, or in most healthcare settings.
In other words, the N95 standard is dedicated ONLY for PROTECTION of the USER.
There is a THIRD standard which combines the ASTM particulate filtration efficiency as specified by ASTM, AND meets NIOSH–approved user-protective N95 standards. These are called the Healthcare Particulate Respirator and Surgical Masks, such as the 3M model 1860. See: https://www.3m.com/3M/en_US/company-us/all-3m-products/~/3M-Health-Care-Particulate-Respirator-and-Surgical-Mask-1860S-Small-N95-120-EA-Case/?N=5002385+3294795977&preselect=8740261&rt=rud
These are typically what are used in the operating room by OR personnel operating working with a contaminated patient or environment, such as a someone with tuberculosis, which would be transmissible TO healthcare personnel, as well as to protect the patient FROM microbes shed by healthcare personnel. Obviously, in a pandemic these would be ideal because it would effectively isolate the user from the rest of the world. Unfortunately, these are in extremely tight supply presently. Explore the 3M site if you want to see how N95 masks are used: They MUST be properly fitted to EACH user EACH time, and have significant limitations in and of themselves. Nevertheless, their biologic/filtering abilities are fantastic & near ideal when properly used & maintained.
As a separate issue, ASTM level 2 or 3 masks, especially when tightened as solidly as possible to the user’s face (I’m referring to surgical facemasks with straps which can be tied, and tension on the straps are adjusted to make the fit really snug… not these sold here), one can actually get filtering efficiency that approaches N95 characteristics. Unfortunately, these masks being sold here look more like procedure masks, and cannot be tightened firmly against the face. Furthermore, I doubt that these are actually rated to ASTM standards, although they may be modeled after one that is. If that’s the case, under the BEST of circumstances, they LOOK like ASTM level 1 masks, used for procedures, not like ASTM Level 2 or 3 surgical masks. But you’d have to test them to verify that. Still, we know that SOMETHING…, indeed ANYTHING, even cloth masks, is better than nothing: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover-guidance.html. What is NOT mentioned by the CDC is the COMBINING of, say, an N95 mask, covered with an ASTM level-1 mask. This could leave more contamination on the level-1 mask, preserving filtering capacity of the underlying N95 or level 3 mask. Several healthcare organizations are doing this to help preserve the supply of their N95 (or level 3) masks . Unfortunately, I don’t think these are ASTM rated, despite their appearance of resembling them (including a layer of blown-polypropylene… the active filtering layer).
Unfortunately, in other words, you’re on your own.
However, if I didn’t have access to anything better, would I use these? YES. Probably better than cloth. Just change them after several hours of use.