Metro 2033
Armor and Stealth suits:
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Before entering the train car at Armory Station, you can purchase a
Stealth Suit for 100 military cartridges from the vendor across from the
Ammo Exchange. There is a vendor next to that one that sells an Armor
Suit that decreases damage. Both suits can be worn simultaneously. A
similar Armor Suit is also sold by a vendor next to the Ammo Exchange in
Polis.
Nightvision goggles:
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In addition to buying the Sneaking Suit at the Armory Station, you can
get a pair of nightvision goggles at Front Lines. While in control of
Artyom, turn around, and follow the train tracks. The nightvision
goggles will be in a red breaker box guarded by two soldiers.
Extending filter:
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Avoid jumping and sprinting to extend the use of your filter.