Most ARC Raiders keys open a single locked room. The Dam Testing Annex Key is one of the few that points you at a building with two locked rooms — a pair of consoles-and-cabinets vaults stuffed with electronics, medical loot, and the occasional blueprint or weapon. The catch is right there in the wiki and every guide that ran it: the key is consumed the instant you open a door, so one key gets you one room. This breakdown gives you the exact building, the route to both doors, and the real loot profile — cross-checked against the ARC Raiders Wiki and the guides that documented the clear.
Quick answer (TLDR): The Dam Testing Annex Key is a Rare, single-use access key (weight 0.25, sells for 100 Coins) that opens locked doors in the Testing Annex — a half-drowned testing center on the southeastern edge of Dam Battlegrounds, between Red Lakes Balcony and the Electrical Tower (arcraiders.wiki). There are two locked rooms, but the key is consumed per door — bring two keys to clear both. You get it from random scavenging (best odds in residential interiors and facilities) or as a reward from the "A Lay of the Land" quest. Inside: valuables lockers, breachable computer consoles, high-value drawers, searchable computer towers, medical bags and a possible Field Depot crate — electronics-, medical- and component-heavy loot with a shot at blueprints and weapons (shacknews). Verdict: a strong, low-risk side room on a mid-traffic map — well worth carrying a key for.
What is the Dam Testing Annex Key in ARC Raiders?
The Dam Testing Annex Key is one of the game's map-specific access keys — consumable items that open a sealed door, then vanish from your inventory. Per the official wiki, it "unlocks a door in the Testing Annex on Dam Battlegrounds" (arcraiders.wiki).
Here are the verified item-card stats:
| Property | Value |
|---|---|
| Rarity | Rare |
| Type | Single-use access key (consumed on use) |
| Weight | 0.25 |
| Vendor value | 100 Coins |
| Stack size | 1 |
| Map | Dam Battlegrounds |
| Unlocks | Two locked rooms in the Testing Annex |
At 0.25 weight the key is effectively free to carry — park it in your safe pocket and run the Dam whenever it spawns. The one quirk that defines this key is the two-door catch: as Shacknews puts it, "there are actually two doors you can unlock with the key, but opening one immediately expends it" (shacknews). One key, one room. If you want both vaults in a single raid, you need to carry two keys.
If you're clearing the Dam keyring, this sits alongside the Dam Staff Room Key — same map, same "find the key, find the door" loop.
How do you get the Dam Testing Annex Key?
There are two routes:
- Scavenging (random drop). The key drops while scavenging — drawers, lockers, filing cabinets and crates inside buildings (arcraiders.wiki). Keys have higher drop rates in residential areas and facilities, so methodically clear interiors rather than chasing open-field loot. There's no way to force the drop.
- The "A Lay of the Land" quest. Completing this quest rewards 1x Dam Testing Annex Key (arcraiders.wiki) — a guaranteed route if you'd rather not fish for the random spawn.
A few practical notes:
- Keep it in your safe pocket. A key in your safe pocket survives a death — never carry your only key in your main inventory into a firefight.
- Bring two if you can. With the per-door consumption, two keys means both rooms in one trip. If you only have one, prioritize the left/first room — guides rate it the higher-value of the two (dualshockers).
- Run it during a Night Raid. DualShockers recommends visiting "during a night raid, since those have better loot drops" (dualshockers) — the major Map Condition lifts loot quality and blueprint odds in key rooms.
Where is the Testing Annex in ARC Raiders?
The Testing Annex is on the southeastern edge of Dam Battlegrounds — the annotated map up top marks it, sitting just south of Red Lakes Balcony and west of the Electrical Tower, between Small Creek and the open water. In-game, inspecting it on the map describes it as "a half-drowned testing center overlooking the red lakes," rated Medium loot value. It's a compact, contained building — not a sprawling tower — which is exactly why it's a low-risk loot stop compared to the Dam's hotter POIs.
Getting in and to the doors:
- The west "milae analyz" entrance. Enter through the west door, where you'll see a sign that reads "milae analyz" — that's how you know you're on the right side (dualshockers). The locked doors are found through the interior from here, in a back hallway.
- The interior route. Shacknews's path runs in from the southern staircase, through a doorway past the red lockers to the northern hallway, then down the stairs and through a door leading south — the two locked rooms open off that corridor (shacknews). Per the wiki, the two doors sit on the south side and the east side of the building at ground level (arcraiders.wiki). Both routes land you at the same pair of doors.
- Block the door behind you. Drop a mine or Door Blocker at the entrance while you loot — the Testing Annex draws other raiders, and you don't want company mid-clear (dualshockers, gamerant).
What's behind the doors — the loot breakdown
The honest caveat first: like every locked room in ARC Raiders, the exact contents are randomized — anyone promising a guaranteed weapon is guessing. What's consistent is the container set in each room. Here's the cross-verified spawn layout:
| Container | Which room | What you pull |
|---|---|---|
| Valuables lockers | First / left room | Mixed-value loot, trinkets, components |
| Breachable computer consoles | Both rooms | Electronics and components behind a breach |
| Drawers (incl. high-value blue drawers) | Both rooms | Mid-to-high-value items and crafting mats |
| Medical bags | First / left room | Medical supplies and consumables |
| Possible weapon case | First / left room | A shot at a weapon spawn |
| Searchable computer towers | Second / right room | Electronic items |
| Loose Technological / Mechanical / Medical loot | Both rooms | Components on consoles and shelves |
| Potential Field Depot crate | Second / right room | High-value crate spawn (not guaranteed) |
Sources: shacknews, gamerant, dualshockers. This is an electronics-, medical- and component-heavy profile with real upside: gamerant notes potential drops of high-quality medical and commercial loot, rare crafting components, blueprints and weapons (gamerant). To show how swingy the RNG is: on one documented run DualShockers' author pulled a weapon blueprint, Sensors, Magnets and Heavy Gun Parts, and on another trip walked out with legendary-tier items (dualshockers). Some runs are quiet; some pay for a dozen keys.
For a 100-Coin Rare key on a contained, mid-traffic building, that's a strong risk-adjusted return — and one of the better blueprint rooms on the Dam when you run it under a major Map Condition.
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Is the Dam Testing Annex Key worth it?
Yes — it's one of the easiest "free value" keys on the Dam. At 0.25 weight the key costs nothing to carry, and the Testing Annex is a contained, mid-traffic building rather than a contested tower, so you're not fighting a crowd to loot it. Each room reliably returns far more than the key's 100-Coin price — electronics, components, medical loot, and a real shot at blueprints and weapons, especially under a Night Raid.
The only real "cost" is the two-door catch. One key opens one room, so if you want both vaults in a single raid you need to bring two keys; with one, take the higher-value first/left room. Block the door behind you, loot fast, and have an extract picked before you commit. For a Rare key this cheap, the Testing Annex pays for itself many times over.
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FAQ
Where do you use the Dam Testing Annex Key? On the two locked doors inside the Testing Annex, the half-drowned testing center on the southeastern edge of Dam Battlegrounds (south of Red Lakes Balcony, west of the Electrical Tower). Enter the west "milae analyz" door, follow the interior hallway to the back, and the two locked rooms sit on the south and east sides of the building at ground level.
How do you get the Dam Testing Annex Key? Two ways: as a random scavenging drop (best odds in residential interiors and facilities — clear drawers, lockers and filing cabinets), or as a guaranteed reward from the "A Lay of the Land" quest.
Is the Dam Testing Annex Key single-use? Yes. It's consumed the instant you open a door, so one key equals one room. To clear both locked rooms in the same raid you need two keys. If you die before using it, it's lost with the rest of your carried gear — keep it in a safe pocket.
What loot is in the Dam Testing Annex? Randomized high-value loot across two rooms: valuables lockers, breachable computer consoles, high-value drawers, searchable computer towers, medical bags, a possible weapon case, loose Technological/Mechanical/Medical loot and a potential Field Depot crate — with a real shot at rare crafting components, blueprints and weapons. Blueprint odds rise under a major Map Condition like Night Raid.
Which Testing Annex room should I open with one key? The first/left room — guides rate it the higher-value of the two, with better odds at higher-rarity blueprints during a Map Condition. Only split your keys across both doors if you're carrying two.
Is the Dam Testing Annex Key worth using? For a 100-Coin Rare key on a contained, mid-traffic building, absolutely. It's low-risk free value — block the door behind you, loot both container sets, and extract. Run it during a Night Raid for the best loot quality.
