diff --git a/core/armor_system.py b/core/armor_system.py
index 599b5b4..8b3352e 100644
--- a/core/armor_system.py
+++ b/core/armor_system.py
@@ -145,11 +145,12 @@ class ArmorPlate:
     item_id: str
     protection: ProtectionProfile = field(default_factory=ProtectionProfile)
     durability: int = 2000  # Plate durability affects economy
+    decay_per_hp: Decimal = Decimal("0.05")  # PEC per HP absorbed
     block_chance: Decimal = Decimal("0")  # Chance to nullify hit completely (no decay)
 
     # Constants
-    BASE_DECAY_FACTOR: Decimal = Decimal("0.05")
-    MAX_DURABILITY: int = 100000
+    BASE_DECAY_FACTOR: ClassVar[Decimal] = Decimal("0.05")
+    MAX_DURABILITY: ClassVar[int] = 100000
 
     def get_total_protection(self) -> Decimal:
         """Get total protection value."""