These are the vests of ATF, what they can handle, etc.
TI VEST: Light (5-7 lb), durable, reliable, and common, this is the TI vest. Most made from a lighter fabric of kevlar, and usually found on police-remnants, as well as on civilians, this is insanely common across the wasteland. Unfortunately, it lacks in armor, only being able to stop 6 - 12 rounds of 9x19mm Parabellum, and only a shot of .45 ACP (will still have bruising).
TIIA VEST: Also light (6 lb), extremely durable, reliable in some factors, there is a reason why the USCPF still manufuncture these. Different from its counterpart, the TIIA vest is meant to be more of a lightweight version, meant for reconnaisance and scouting operations. It is also extremely flexible, matched to move with the arms and torso, as well as the waist. It sustains a far greater protective use for its user, being able to stop 20 rounds of .45 ACP at most, and 5 rounds of the .454 Casull.
TII VEST: Balanced in weight (8 - 10 lb), flexible, durable, and reliable, this a force to be reckoned with, so far that the CDF considers it "military grade". The TII vest: the first layer a bendable kevlar, the second layer polyurethane exterior, stopping the projectile in its track. Mainly used by DECorp mercenaries, as well as USCPF on standard operations, their choice was excellent in using this. Being able to stop .223 Remington rounds (12) at most, this was reasonable use.
TIIIA VEST: A bit weighty (10 - 14 lb), powerful, durable, yet uncomfortable, this is the TIIIA vest. These were the key vests used in the ACMF-NATO war. Made from two-layers of polyurethane, these vests had more capability of the stopping power of a TII vest had. Sadly, this is not manufactured anymore due to its expensive fabric and materials, as well as weight. It can stop eight rounds of 6.8x43mm SPC, as well as twelve rounds of 5.56x45mm
TIII VEST: Common and recognizable among the NATO and ACMF, the TIII vest is a heavy (14 - 16), durable, and reliable vest. Made from three-layers of polyurethane, as well as a kevlar exterior on the fabric for outside, there was a reason why this wasn't produced anymore. It was too expensive to produce as well as the weight. Being able to stop eight rounds of 7.62x39mm, this was a popular choice among the NATO-ACMF standard troops.
TIV VEST: Heavy, durable, unreliable, and expensive, the TIV vest. This vest is made from two-layers of Dragon Skin (yes this is a real material, made by Pinnacle Armor), as well as an extra layer of polyurethan. This was extremely heavy (18 - 22 lb), uncomfortable, and expensive, as there was a reason why Heavy Troopers of the ACMF were equipped with this. It can stop two rounds of .300 WinMag at best.