Here is some history and things as explained to me by MSA brand managers for North America over the years:
SORDIN was purchased by MSA, MSA started distributing SORDIN muffs, branded MSA in the USA though the MSA Authorized dealer network.
SRS Tactical was not a MSA dealer, but they were importing SORDIN branded muffs from SORDIN's European dealers. There was nothing illegal about this that I was ever aware of, MSA just didn't like it. Since these were being imported into the US outside of the MSA network, MSA considered them to be "grey market" products and MSA North America would not cover them under the warranty. This meant SORDIN branded muffs from SRS were not covered and would have to be sent back to the last authorized dealer point, which in this case somewhere in Europe, for service.
If you were shopping for muffs in the US and saw SORDIN on the ear cup, you could be pretty certain in was a grey market import. If the ear cup said MSA on it, you were getting something that came in through MSA authorized dealer network.
So why does it matter? MSA had standardized the electronic components on models they had submitted for testing(OSHA?) and NRR certification in the USA. These were the models they were prepared to warranty and service in the USA. SORDIN could, and apparently did, change certain components in the Euro models they were distributing over there. This would mean the US service center would be unable to work on these muffs if they ended up in the USA.
I heard from a lot of people that bought Euro SORDINs that tried to get service from MSA in the US and were told they had to ship them back to Sweden for service. Just a couple hundred dollars in shipping. I did also hear from a few people that had sent broken muffs back to SRS for service. I don't think they were serviced, but replaced since they had no way to service them.
I used my first pair of SORDINs in 2005 (still use that pair all the time BTW) and Triad became MSA dealer a couple years later. I was constantly pushing MSA to improve the offerings to include the OD ear cups, the headband models to the US market (which they did). Triad was the first US authorized dealer to offer the silicon gel rings as a factory installed option. Triad sold a lot of MSA muffs over the years, but we parted ways over the Amazon thing.
I have not looked at the status of MSA/SORDIN for a couple years, no dog in the fight anymore, but as always buyer beware.