Hands down, tese are the best - Guard Dog Body Armor Ultralight Level IIIa Ceramic Plate

They weight nothing. I don't even notice it's there. I armored up a maxpedition Kodiak gearslinger bag for work. Not that my job is extremely dangerous but it's comforting to know I have it. I got some heavy duty Velcro for securing sofa pads and used that to keep it in one place in my bag. My bag has loop panels and the hook Velcro did the trick. Its really cheap by comparison to other products and I don't care for soft armor. I don't mind it only being 3a, because that's most likely what I'll run into. Like I said it weighs nothing in comparison to level 3 steel plates. You really can't beat it.