DeWalt 1/4 in Drive 6 Point Deep Metric Socket (4 mm)

Why a 4 mm deep socket matters more than you think

Tiny fasteners can be fussy, and a poor-fitting socket is the quickest way to round one off or send it flying across the shop. I put the DeWalt 4 mm deep socket into my everyday kit to handle small hex-head hardware—think M2 nuts and similarly sized fasteners—on robotics builds, electronics housings, and recessed standoffs. It’s a simple, single-size tool, but in practice it solves a handful of very specific problems with a confidence that cheaper micro sockets don’t always deliver.

Design and build

This is a 1/4-inch drive, 6-point deep socket with a polished chrome vanadium finish. The finish is smooth enough to wipe clean quickly and has held up well after a few months of oily bench work and the occasional solvent splash. The machining on mine is tidy: crisp hex corners inside, clean chamfers, and no burrs. DeWalt’s knurled control ring encircles the socket body near the nut end and provides useful grip for finger-spinning fasteners without reaching for the ratchet.

Size markings are hard-stamped, not laser-etched. That’s a small but meaningful difference on a socket this small—etched markings can fade under regular cleaning, while stamped numbers stay readable. The geometry inside uses DeWalt’s “DirectTorque” approach, biasing load onto the flats of the fastener rather than the corners. In this size range, that matters; there’s not much material on a 4 mm head, and corner contact is a recipe for rounding.

Key dimensions (measured and cross-checked with the spec sheet):
- Overall length: 1-15/16 in
- Bolt clearance depth: 1-5/8 in
- Nut depth: 3/16 in
- Nut end outside diameter: 9/32 in
- Drive end outside diameter: 15/32 in

The outside diameters tell you this isn’t a “thin-wall” specialty socket, but it’s reasonably slender. I’ve fit it into most plastic boss recesses and small metal channels that smaller hardware tends to live in.

Fit and engagement

On 4 mm hex heads (which correspond to very small screws and M2 hex nuts in many standards), the fit is positive with minimal rotational play. The 6-point profile grabs where it should—squarely on the flats—and releases cleanly. I tested it on a batch of mixed hardware: black oxide machine screws with slightly rounded heads, zinc-plated standoffs, and a few stainless pan-heads with shallow hex heights. The socket tolerated those shape inconsistencies better than expected. On the most abused fasteners, it still bit enough to turn without slipping.

The chamfer at the mouth is subtle, which helps start the socket onto tiny heads without skating off. I prefer this to overly aggressive chamfers that trade ease of entry for less engagement on shallow nuts. Combine that with the knurled ring and it’s easy to start hardware by hand before you bring in a ratchet.

Depth and access

Deep sockets in small sizes earn their keep around standoffs, panel hardware, and recessed bosses. The 1-5/8 in bolt clearance depth provides generous room for studs or long screws, and the 3/16 in nut depth is plenty for the thickness of small hex nuts and bolt heads. I’ve used it to remove nuts at the bottom of narrow plastic wells on an enclosure lid; it reached without needing an extension, and the nut end OD of 9/32 in was narrow enough to clear the walls.

Where it struggles is in ultra-tight electronics cavities, the kind where a thin-wall or purpose-built nut driver is the only thing that fits. If your work routinely lives inside those constraints—camera bodies, watch cases, compact drone frames—you might still want a dedicated thin-wall or hollow-shaft nut driver. For general small hardware, this socket’s proportions strike a good balance between strength and access.

In use: control and torque

With tiny hardware, torque control is everything. I primarily run this socket on a small 1/4-inch palm ratchet, a spinner handle, and a torque screwdriver via a square adapter. The knurled ring makes fine adjustments easy; you can spin a fastener down quickly by hand with a confident grip, then switch to a ratchet for the last quarter-turn. When paired with a torque screwdriver, it delivers even, repeatable tightening without drama.

The DirectTorque-style internal profile earns its keep under break-loose loads. On small zinc fasteners that had picked up corrosion, the socket broke them free without shaving corners. It’s not magic—you can still overwhelm a 4 mm head with too much force—but it gives a better margin than generic 12-point micro sockets.

One note: this is a standard chrome hand socket, not an impact socket. Don’t use it on an impact driver. If you need powered assistance, a low-speed electric screwdriver with a gentle clutch is a safer match.

Durability and maintenance

Chrome vanadium sockets live or die by heat treat and quality control. Mine shows even plating, no flaking, and no distortion after repeated use on small fasteners that were tighter than they should have been. The drive square tolerances are good; there’s no slop on ratchets or extensions. The knurling is fine enough that it doesn’t chew up fingertips but still catches when your hands are oily.

Cleanup is straightforward: a quick wipe and the chrome looks new. The stamped size marking stays readable despite frequent solvent-wet rags. If you magnetize your sockets for small hardware, this one takes and holds magnetism predictably; it will retain tiny nuts well enough to guide them into place, though it’s not a dedicated magnetic socket.

Comparisons and context

Against lower-cost “micro” deep sockets, the most noticeable differences are:
- Tolerances and bite: This 6-point profile holds better on imperfect hardware than bargain 12-point sets.
- Markings and usability: Stamped size and a functional knurled ring matter more on small sockets than they do on larger ones; you’re constantly picking and placing them.
- Wall thickness: Not thin-wall, but slimmer than some generic deep sockets in the same size, improving access without feeling fragile.

Against a thin-wall nut driver, the trade-off is strength versus reach profile. Nut drivers often sneak into tighter spaces and are great for repetitive work on the same hardware. The DeWalt socket, however, interfaces with your existing 1/4-inch drive ecosystem—ratchets, extensions, torque tools—so it adapts better to mixed scenarios and break-loose tasks.

Limitations

No single small socket is perfect. A few things to keep in mind:
- Not thin-wall: It won’t fit the tightest cavities where a thin-wall or specialized nut driver is required.
- No magnetic insert: If you rely on magnetized sockets for initial placement, you’ll need to magnetize it yourself or use a retaining insert.
- Deep length can be a constraint: In some cramped assemblies, the extra length of a deep socket can interfere with nearby parts; a shallow 4 mm option can be a good companion.

None of these are dealbreakers in general use, but if your work skews toward ultra-compact assemblies, plan your kit accordingly.

Who it’s for

If you build or service small machines, 3D printers, robots, instrumentation, or electronics enclosures that use tiny hex-head hardware, this socket earns a place in your roll. It’s equally at home for hobbyists working on miniature mechanisms and for pros who need a reliable way to break free small fasteners without drama. If your fasteners are predominantly socket-cap screws (internal hex) rather than hex heads, you’ll get more mileage from a quality hex bit set—but keep this around for the nuts and standoffs that inevitably show up.

Recommendation

I recommend the DeWalt 4 mm deep socket. It hits the fundamentals—accurate 6-point engagement, useful knurled grip, durable chrome vanadium finish, and clear stamped size—and avoids the pitfalls that plague cheap micro sockets. It’s not a thin-wall or magnetic specialty piece, so it won’t solve every tiny-fastener challenge on its own, but as a reliable, adaptable 1/4-inch drive socket for small hex heads, it has performed exactly as I expect a professional hand tool to perform. If your work involves M2-size nuts, recessed standoffs, or any small hex hardware where rounding is a risk, this socket is a smart, dependable addition to the drawer.