M3–M5 Flat Head Slotted Machine Screws — Flush-Fit 304 Stainless Steel for Precision Assembly
When a protruding screw head isn't an option — in electronics enclosures, furniture hardware, or precision fixtures — you need a countersunk screw that sits perfectly flush. These M3–M5 flat head slotted machine screws are built for exactly that: clean, flush installation in pre-tapped holes where surface clearance matters. DIYers, makers, and maintenance professionals who work with metric hardware will find these an essential stock item.
Each screw is machined from A2 grade 304 stainless steel with a plain (uncoated) finish and passivated surface for added oxidation resistance. Available in thread sizes M3, M4, and M5, with lengths from 5 mm (≈0.20 in) to 30 mm (≈1.18 in), and sold in packs of 5, 10, 20, 50, or 100 pieces. All screws are fully threaded with metric coarse pitch (M3×0.5, M4×0.7, M5×0.8).
Typical use cases include securing panels in electronics projects, assembling aluminum extrusion frames, mounting hardware in cabinetry, and general metric machine screw applications where a flush countersunk flat head slotted fastener is specified.
⚙️ Thread Standard: Metric Coarse (ISO 68-1) — M3×0.5 / M4×0.7 / M5×0.8. Requires a pre-tapped hole or nut. Not self-tapping.
✅ Key Features of These M3–M5 Flat Head Slotted Machine Screws
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🔩A2 / 304 Stainless Steel: Corrosion-resistant and passivated — suitable for outdoor, humid, and mildly acidic environments without rusting under normal conditions.
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📐Countersunk Flat Head: Angled underside seats flush in countersunk holes, eliminating protrusion for clean, snag-free surfaces.
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🪛Slotted Drive: Compatible with any standard flat-blade screwdriver — no specialty bits required for installation or removal.
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🔗Fully Threaded Shank: Thread runs the full length of the shank for maximum engagement and holding strength in tapped holes.
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📦Flexible Pack Sizes: Choose 5, 10, 20, 50, or 100 pieces — stock up for a project or grab a small quantity for a quick repair.
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📏Wide Size Range: M3 (5–30 mm), M4 (6–30 mm), M5 (8–30 mm) — covers the most common metric machine screw sizes in a single listing.
📐 Technical Specifications — M3–M5 Countersunk Flat Head Slotted Screws
| Material |
A2 / 304 Stainless Steel |
| Head Style |
Flat / Countersunk |
| Drive Style |
Slotted |
| Thread Type |
Metric Coarse (ISO 68-1) |
| Thread Pitch |
M3: 0.5 mm | M4: 0.7 mm | M5: 0.8 mm |
| Available Sizes |
M3×5–30 mm / M4×6–30 mm / M5×8–30 mm |
| Pack Quantities |
5 / 10 / 20 / 50 / 100 pcs |
| Finish |
Plain (Passivated) |
| Shank |
Fully Threaded |
| Length Measurement |
Top of head to tip (full length embedded when flush) |
| Grade |
A2 (304 SS) — See variant options for size |
📌 Stainless Steel Grade Guide: 201 SS — dry indoor use only, prone to rust with moisture. 304 SS (A2) — this product — outdoor/humid environments, good corrosion resistance. 316 SS (A4) — marine/chemical environments, highest corrosion resistance.
❓ Frequently Asked Questions
What sizes are available?
These screws are available in M3, M4, and M5 thread diameters, with lengths ranging from 5 mm to 30 mm depending on the size. Select your combination using the Screw Size and Item Length options above.
Are these metric coarse or fine thread?
Metric coarse thread. Pitch is typically 0.5 mm for M3, 0.7 mm for M4, and 0.8 mm for M5 — standard ISO metric coarse specification.
Will 304 stainless steel rust outdoors?
304 (A2) stainless steel is generally suitable for outdoor and humid environments with good resistance to corrosion and mild acids. For marine or highly corrosive environments, 316 (A4) is recommended.
How is the screw length measured?
Length is measured from the top of the flat (countersunk) head to the tip. The full stated length is embedded when the screw sits flush in a countersunk hole.
What screwdriver do I need?
A standard flat-blade (slotted) screwdriver in the appropriate width for M3, M4, or M5. No specialty bits required.
Are these screws fully threaded?
Yes — all screws in this listing are fully threaded from tip to just below the head, providing maximum grip across the entire shank length.
Can I use these in wood or plastic?
These are machine screws for pre-tapped holes or nuts — not self-tapping. For wood or plastic, a tapped insert or nut is typically required.
🛒 Select your Screw Size, Item Length, and Qty above, then add to cart
