If you want multi-strike military grade, good luck. These are hard for civilians to get and may get you thrown under the jail. There is several DHS task forces running right now tracking down stolen armor from the military being sold out of country.
You may be able to get Dragonskins. These are multi-wafer ceramic discs and are kind of setup like chain-male (sp?) and will take multi-strike. They claim CL4 (I believe) and are 50% lighter than the old military ceramics that were single strike.
I was just about to pull the trigger (no pun intended) on buying a full set of tactical from them and backed out. Now I do not have the extra change to do it. Kick myself in my big arse every time I think about it. I have two phone numbers for Dragonskins and a contact name I will FReepmail you.
Thanks!