Question: how thick are kevlar vests?
Answer: Level III-A vests are 0.33" thick (8 to 9 mm) and are concealable, but tougher to stop them from "printing" under light clothing. Rifle Plates are generally an extra 0.25" to 1.0" thick (6 - 25 mm) and thus require a jacket, sweater, Battle Dress Uniform, etc., etc. to conceal.