Stealth Armor
From BattleTechWiki
Stealth Armor is a special type of armor which does not provide more protection per ton or more protection against a certain attack type, but makes the armored unit harder to hit. The unit becomes harder to hit the further away it is from the attacker, in addition to the normal penalties for range and other factors. In order for this armor to function, an ECM suite must also be included.
