SentrySafe Black Fireproof and Waterproof Safe, File Folder and Document Box with Key Lock, Ex. 14.3 x 15.5 x 13.5 inches, HD4100

Why I picked this file safe

I bought the HD4100 file safe to corral passports, birth certificates, insurance documents, and a few thumb drives that had been living in a shoebox. I wanted something compact, reasonably priced, and actually rated for both fire and water. After several weeks of use—loading it up with hanging folders, tucking it away in a closet, and running a few practical tests—I’ve got a clear sense of where this box excels and where it doesn’t.

Build and capacity

The exterior is a plain black shell that’s all business. It’s not flashy, and it doesn’t try to be. The footprint (about 14.3 x 15.5 inches) and height (around 13.5 inches) make it easy to slide onto a closet floor or under a desk, yet the body is chunky because of the insulation needed for its fire rating. Inside you get 0.65 cubic feet of storage—enough for a neat row of letter-size hanging folders, a few manila folders, and slim binders. My thinner 3-ring binder fits; bulky binders do not.

If your world runs on letter-size paper, you’re in good shape. Hanging rails inside are sized for standard US letter folders and the fit is snug—in a good way. If you work with a lot of A4 documents, this isn’t the box for you. A4 sheets will sit awkwardly, and A4 hanging folders won’t fit the rails.

Under the lid, a pair of built-in straps holds passports, spare credit cards, or a small envelope of emergency cash. They’re handy for flat items you want quick access to, but they’re not elastic pockets, so think of them as keepers rather than storage.

Fire and water protection

This is the HD4100’s reason for being. It’s UL Classified to withstand a 30-minute fire at 1550°F, which is the standard entry-level protection for home document safes. That rating is geared to keep the interior below the temperature that would destroy paper documents and digital media like USB drives and DVDs for that window of time. I didn’t simulate a house fire, obviously, but the construction and the gasketed lid are consistent with other UL-rated boxes I’ve used. For most homes, 30 minutes is a reasonable minimum; if you live far from a fire station or want belt-and-suspenders protection, step up to a one-hour unit.

Water protection is where this box differentiates itself from a lot of “fire-only” chests. It’s ETL Verified for 72 hours in up to 8 inches of water—think burst pipe or a shallow flood. I ran a modest test: I placed paper towels inside, latched and locked the lid, and set it in a shallow tray of water for several hours. The towels came out dry. That doesn’t prove anything about multi-day flooding, but it does give me confidence that splashes, high humidity, and short-duration pooling aren’t going to wick in. I still put sensitive electronics in small zip-top bags—a cheap extra layer that costs almost nothing.

One practical note: protection ratings assume the box stays closed and properly latched. Don’t overload the interior so much that the lid can’t fully compress the gasket.

Locking and actual security

The key lock here is simple and flat, and you get two keys. It’s there to keep the lid shut and prevent it from popping open during a fire, not to foil a determined thief. If you need theft resistance, you’re looking for a safe with a solid steel construction, better locking bolts, and a way to anchor it. The HD4100 is a document chest with a lock, not a burglary safe. For my use—privacy at home and travel-proofing against curious hands—it’s adequate.

The latch action was a bit stiff the first few times. It loosened up with use, but I’d still advise turning the key fully before lifting or closing the lid. Don’t use the handle as leverage to pry it open if it’s locked; you’ll feel the handle flex if you try.

Day-to-day usability

Two things stand out in daily use. First, it’s heavy for its size. That’s part of the fireproof formula, but it does make moving it a little awkward. There are no side handles and the surface is fairly smooth, so gripping it with one hand feels dicey. I solved this by setting it on a small dolly so I can roll it out to access files and roll it back into a corner. If you plan to move it frequently, plan for the weight and consider where it will live before loading it up.

Second, the lid has no soft-close or damping. If you let it fall, it will slam. I open and close it with two hands to guide the lid and protect the gasket. Speaking of the gasket: it’s the critical barrier for smoke and water, and on mine it’s seated well. I make a habit of checking that it’s aligned before closing—good practice for any gasketed chest.

Organization and workflow

As a file box, it’s straightforward and effective. Standard hanging folders drop right in, and the snug spacing makes flipping through them feel tidy. I use the lid straps for passports, spare apartment keys, and a single USB drive with encrypted backups. Larger valuables and bulky items quickly steal space from file capacity, so if you intend to store cameras or jewelry boxes alongside paperwork, you’ll run out of room faster than you expect.

To make the most of the 0.65 cu ft, I adopted a few habits:
- Use slim, flat file folders for certificates and titles; avoid thick binders unless absolutely necessary.
- Label the top tabs clearly so you don’t keep the lid open longer than needed while searching.
- Add a couple of silica gel packs to help with humidity.
- Keep one key hidden in a separate location and one with a trusted person.

Placement and practical considerations

Water ratings assume rising water depth, which is a good argument for storing a waterproof chest at or near floor level rather than on a high shelf where it might fall. I placed the HD4100 on a low shelf inside a closet, on a rolling base. That gives me easy access without the risk of dropping a heavy box from shoulder height.

Because this is not an anchored safe, think about concealment. Tuck it out of obvious sight. If theft is a top concern, use this as a fire/water document stash and pair it with a more secure safe for valuables.

Where it fits—and where it doesn’t

The HD4100 is ideal if:
- You need a compact, affordable way to protect letter-size documents against fire and water.
- You value simple organization with hanging files.
- You don’t plan to move it frequently once it’s placed.

It’s not ideal if:
- You use A4 documents or A4 hanging files; the dimensions just don’t support them.
- You want burglary resistance or anchoring options.
- You require a one-hour (or longer) fire rating.

Durability and maintenance

The outer shell feels solid and the hinge has held up to frequent openings. Keys are thin and flat—keep them in a protective key sleeve so they don’t bend in a junk drawer. Wipe the gasket and mating surfaces occasionally so dust doesn’t compromise the seal. If you ever feel the lid meeting resistance, stop and check for a folder tab or passport corner catching the gasket.

Value

For the features—UL 30-minute fire protection, ETL 72-hour water protection, letter-size file rails, and a compact footprint—the HD4100 hits a sweet spot. You can spend more for longer fire ratings or heavier construction, and you can spend less on boxes with no meaningful testing. Here, you’re paying for certified protection and sensible organization without creeping into “small safe” pricing.

Recommendation

I recommend the HD4100 file safe for anyone in the U.S. who needs to protect letter-size documents and a few small valuables from fire and water, without stepping up to a full-size safe. It’s heavy but compact, simple to use, and appropriately rated. The lock provides basic privacy and keeps the lid secured under stress, while the hanging file rails make everyday organization painless. Just be aware of its limitations: it’s not a theft deterrent, it doesn’t accommodate A4 systems, and moving it is awkward. If those constraints don’t apply to you, this is a practical, affordable way to add real protection to the documents you can’t replace.