Just a snippit of input - I'm familiar with the 7x12, it's a Second Chance K-30 plate for female armor. The angle is designed to let it sit more naturally over the female anatomy, and it is a chest plate rated for 9mm AP, .30 carbine, and .44 Magnum 16in. carbine rounds, but not rifle rounds like .308 or .223. It's an upgrade plate for police vests, rather than a true level III rifle plate, and a definite step above most trauma plates.
Good luck with your sale!