DayZ field wiki · Gear
Armor
Plates eat the vault
Short answer
A plate carrier is a life and a slowness. Helmets are a head. Holes dump the point.
Also: armour · vest
How it works
Ballistic vs cosmetic is a real difference. This is not a damage-reduction table.
What to do
Wear it for towns. Consider dumping it to swim.
Don't
Don't treat a construction helmet as a ballistic one.