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M3 x 4mm Screws

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M3 x 4mm screws are the usual size for fixing 2.5" SATA SSDs and laptop hard drives into brackets, caddies and NAS drive bays, and for some video-doorbell terminal screws. The short 4 mm length engages the drive threads without reaching the circuit board inside.

Most 2.5" drives have four threaded holes on the bottom and four on the sides; which set you use depends on the bracket or caddy. Check the holes with a known M3 screw before you start, and never force a longer screw into a drive. Measure an old screw with calipers: the thread diameter gives the M number and the length gives the second figure. On a countersunk head the length is measured overall, head included; on a flat-bottomed head it is measured from under the head to the tip.

Related sizes: M3 x 6mm · All M3 screws · HDD brackets & caddies

Fit guides: Ring Doorbell screw guide (M3 x 4mm) · Google Nest Doorbell screw guide (M3 x 4mm)

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How do I know these screws will fit my device?

Every listing states the exact metric thread, length, head type and finish. Match it against your original screw, your model's page in our model guides, or measure with the finder tool. If it's still wrong, we make it right.

Can I buy just one screw?

Yes — that's our specialty. Most sizes are sold as single screws, with 10-packs, 50-packs and 100-packs for shops and fleets. Each cart line needs to reach $4.99, so very low-priced singles are added in a small multiple.

How fast is shipping?

Orders usually ship within 24 hours (Monday to Saturday) from Elgin, South Carolina, with tracking. US orders of $25 or more ship free, and typical US transit is 1 to 5 business days. See the shipping policy.

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