My M3 SR+ is late Aug 2020. My filter is very new, but I was tempted by HEPA filters. In my neck of the woods I can order from T$%B*& for pretty cheap prices, but instead I went on Amazon USA and ordered it, hoping for better QC. Stock is made in Germany, and this one from Amazon, is PRC. Honestly, it lacks precision. The red ribbon is kinda flimsy and cheesy. Hardly as strong as the tab on the stock. The carbon is the odd part. It's beads and they are loose and there are huge gaps between them. It makes me wonder how it can absorb chemicals and smells. The white filter on the other side, by eye judgment actually seems fine. But, I did not go out to buy any type of meter to check the air quality, etc. The packaging that came with it, was just a box really, not much printed on, and no documentation proofing that it is indeed HEPA level or even what HEPA level. Built is poor. Filter is paper like, housed around by a plastic rectangle, which is very filmsy. I accidentally broke one when I was removing it from the box. In the end, I benched it. I found a brand called LUFTT. When i got it, I was blown away by the quality (or by eye judgment), packaging is superb, detailed description printed on the box. Carbon is blended into a mesh rather than just a bunch of loose carbon bits. Tabs attached to the filter are built almost exactly like the stock version. If you go on the website (easily found), it provides on the documentation of testing/validation. It clearly states this is HEPA level 10. Clearly printed on the filter, it is made in Korea. Again, I did not conduct any testing, but overall, I believe it is indeed HEPA level filter. The other one, I am not sure if it is really HEPA, or at least, HEPA with respect to HEPA standard. There are other brands on Amazon, claiming to be HEPA or made by 3M, but I can not never find any proof. It's just a claim. In the end, I replaced the stock filter with the LUFTT. No regrets, All seems good.