I was looking at the common SRT plates, the Tencate 6450 and it's derivatives, the Hesco U210 and the LTC 28720, and I couldn't find info on their drop testing. Do these plates meet the NIJ 101.06 drop test standard?
To my knowledge, the TenCate 6450, Hesco U210, and LTC 28720 are entirely different plates and none of them are derivatives of eachother since they each come from a different OEM. I checked the 0101.06 CPL for you for the 6450 (D1684), U210, and LTC 28720 and found that none of them are NIJ Certified. This indicates that the plates will most likely not pass the 0101.06 drop test that is part of the certification process.
The NIJ 0101.06 CPL for reference:
From Hesco's website for the U210: "NIJ Standard-0101.06: Special threat testing conducted in accordance with NIJ Standard-0101.06 (modified)."
Tencate lists the 6450 as NIJ Level III+ and technically to test for any NIJ level compliance the testing must be done by an accredited independent/third party lab. Unlikely that they would specifically omit the drop testing but you never know.
Couldn't find anything on the LTC.
I would give the manufacturers a call and ask outright about the specific plates you are interested in.
If I recall correctly, there is no need to actually test for "compliance" at an accredited independent or third party lab. That's done when you want to test for certification, but most vendors will do a compliance check with an accredited lab to prove that they're selling a product that will do what it is advertised to do. Unless the armor has proof that it can pass the drop test, then you should never really assume that it will. That's functionally equivalent to a plate not advertised to stop something like M193 being assumed to stop M193. Nonetheless, I agree with MAX K that calling the manufacturers is the best bet.
The LTC 28720 is some astronomically high-end $1,200 plate that provides protection equivalent to the 6450 but at 10% lower weight. To the best of my knowledge, it constitutes the BZ-rating end of LTC's ultra-premium line that consists of the 28720, the 28601 (XSAPI), the 28595 (Tactical Standalone GEN V) and a few others.