Armor Factor
Armor factors derive from your skin and the gear you are wearing. Two numbers show the total effectiveness of armor, separated by a %.
e.g. 5% 12hp.
The first number is the percentage of damage that is absorbed by armor.
The second number is the amount of damage that is blocked by armor.
Hit points of damage are absorbed then blocked.
e.g. A knife is used to hit a target with a 20hp strike vs the target's 5% 12hp armor. The calculation to solve that looks like this: 20hp - (.05 * 20hp) - 12hp = 7hp unblocked damage. The unblocked damage is what the amount that gets through your armor, reducing your health, by 7hp in this example.
Armor factors on the Gear window are shown for kinetic contact damage. Armor factors can vary considerably against other weapon effects and modes.
Armor Wear
Armor gear degrades 1 point for every 10hp of damage it reduces; hardened armor degrades only 1 point for every 20hp, when hit by the type of damage it is hardened against.
Environment armor and helmets lose their ability to protect against the environment when reduced to zero condition points. Inspecting these items will report the environment seal as broken when this is the case.