Armour can save your life but taking hits with bullets will eventually wear things down. So in the Verse, armour comes with an armour rating. The rating in games terms is how often you can get hit before the armour can fail you. So an AR of 4 means you can take 4 shots to the armour before the plates give up. After 4 shots, the armour has a 25% chance of failure, then a 50%, than a 75% and then it is done for sure. I am assuming all armour owned by crew is Tier 1.
Tier 5 (AR 8 to 10) - Alliance armor, Generation X Carbon Nanosteel plating (Extremely valuable, accessible only to Alliance military)
Tier 4 (AR 7) - High grade armor, Generation VIII Draconis Steel plating (Highly valuable, accessible to Alliance military, rarely seen on black market)
Tier 3 (AR 6) - Medium grade armor, Generation V Amphorite Steel Plating (Valuable, accessible on black market, discontinued by Alliance military)
Tier 2 (AR 5) - Low grade armor, Generation II Reslin-Modernis Steel Plating (Uncommon, available for purchase legally with private security license, openly available on black market)
Tier 1 (AR 4) - Personal security armor, Generation I Torin-Black Ceramic Plating (Common, openly available for purchase)
Cheap gear and knock offs(AR 1-3) - When you can't afford the very best, there is Al's disposable body armour. Comes with a free body bag.