304 (A2)
Security / Tamper-Resistant Screw
Tamper-resistant security screws, pin-Torx, pin-hex, one-way and snake-eye drives that need a special bit to remove, including anti theft number plate screws.
About the Security / Tamper-Resistant Screw
Security screws need a special bit to undo, so they stop theft and vandalism on number plates, signs, toilets, playgrounds, letterboxes and public fittings. They are 304 stainless with pin Torx, pin hex, snake-eye and one-way drives, as self-tapping screws from #6 to #14 and machine screws from M3 to M12 and 3/8 UNC, with button, countersunk, pan and raised countersunk heads. Choose the drive, head, size and length above; the guide below covers each drive, the bit it takes and fixing number plates.
Also called tamper proof screws, anti theft screws or tamper proof bolts.
Features
- Pin-Torx, pin-hex, one-way and snake-eye drives
- Button, countersunk and raised heads
- Machine and self-tapping threads
- 304 (A2) stainless
Applications
- Fixings in public facilities
- Anti-theft number plate fixing
- Signs, toilets, playgrounds and public facilities
- Fences, gates and letterboxes
How tamper proof screws work
A security screw has a drive that ordinary screwdrivers and bits cannot turn, so it stays put in public places and on anything worth stealing. Each drive needs its own matching bit to fit or remove it.
- Pin Torx: a six-point star (Torx) recess with a pin in the centre. A standard Torx bit will not go in; it takes a security Torx bit with a hole for the pin. The star shape grips well, prevents cam out and lets you apply more torque.
- Pin hex: a hex socket with a centre pin, driven with a pin hex bit or key that is bored down the middle to clear the pin.
- Snake-eye: two small holes in the head, driven with a matching two-pin eye drive bit.
- One-way: a slot shaped so a flat screwdriver drives it in but has nothing to grip to undo it. Use it where the screw never needs to come out.
Choosing the head and thread
- Button head: a low, rounded head that sits on the surface. Pin Torx and pin hex.
- Countersunk head: sits flush in a countersunk hole. Pin Torx, pin hex and snake-eye.
- Pan head: a raised flat-topped head, in snake-eye.
- Raised countersunk: the one-way screw, with a slightly domed countersunk head.
- Self-tapping (#6 to #14): forms its own thread in a pilot hole in sheet metal, plastic or timber.
- Machine thread (M3 to M12, 3/8 UNC): fits a tapped hole, a nut or a threaded insert, and can be undone and refitted with the right bit.
Security screw sizes and the bit each one takes
Every size we carry, with the security bit each drive needs. Order the bit with the screws: without it you cannot drive them, or get them out again later.
Bit sizes from the screw descriptions and the maker's data sheets. Snake-eye bits are numbered; pin hex sizes are in mm. Self-tapping lengths are in inches, machine screw lengths in mm. Not every length comes in every head and drive: brackets show lengths only some types have, and the selector shows exactly what each one has. Tap a number to show it in the selector above.
| Size | Thread | Pin Torx bit | Pin hex bit | Snake-eye bit | One-way | Lengths |
|---|---|---|---|---|---|---|
| Self-tapping (gauge) | ||||||
| #6 | Self-tapping (gauge) | T10 | No. 6 | 3/8 to 1-1/2 inch (3/8 pan snake-eye only; 5/8 snake-eye only) | ||
| #8 | Self-tapping (gauge) | T15 | 2.5mm | No. 8 | Yes | 1/2 to 1-1/2 inch (5/8 snake-eye only; 1-1/4 pin Torx only) |
| #10 | Self-tapping (gauge) | T20 (countersunk), T25 (button) | 3mm | No. 10 | Yes | 1/2 to 2 inch (5/8 snake-eye only; 1-1/4 pin Torx only; 2 inch pan snake-eye only) |
| #14 | Self-tapping (gauge) | T27 (button), T30 (countersunk) | No. 14 | 1/2 to 1-1/2 inch (1/2 pan snake-eye only) | ||
| Metric machine thread | ||||||
| M3 | Metric machine thread | T10 | 6 to 20mm | |||
| M4 | Metric machine thread | T20 | 2.5mm | No. 8 | 6 to 70mm (40 to 70mm countersunk pin Torx only) | |
| M5 | Metric machine thread | T25 | 3mm | No. 10 (countersunk), No. 12 (pan) | 8 to 60mm (8mm countersunk pin Torx only; 40 to 60mm pin Torx only) | |
| M6 | Metric machine thread | T30 | 4mm | No. 12 (countersunk), No. 14 (pan) | 10 to 60mm (60mm countersunk pin Torx only) | |
| M8 | Metric machine thread | T40 | 5mm | 16 to 80mm (80mm pin Torx only) | ||
| M10 | Metric machine thread | T45 | 16 to 50mm | |||
| M12 | Metric machine thread | T50 | 30 to 70mm | |||
| Imperial machine thread (UNC) | ||||||
| 3/8 UNC | Imperial machine thread (UNC) | T45 | 15 to 82mm | |||
Anti theft number plate (rego plate) screws
Number plates (rego plates or licence plates) are a common target for theft. Swapping the plain screws for security screws means the plate cannot come off without the matching bit.
Match the screws you are replacing. Take one out and check whether it is a self-tapping screw (a pointed screw that cuts into a plastic plug or the panel) or a machine screw (a blunt end that goes into a threaded hole or nut), then measure its diameter and length. We carry both kinds in 304 stainless, so you can match the thread and choose the drive. The screws are sold in packs, mostly of 100 (some sizes in packs of 25, 50 or 200), and the bit is a separate item, so add one to the order. Keep the bit in the car so you can take the plate off when you need to.
304 stainless and where to use it
All our security screws are 304 (A2) stainless steel, for signs, toilets, playgrounds, public facilities, fences, gates, letterboxes and vehicles. Stainless needs only light care: wash off grime and salt so it stays bright. Rust spots on stainless usually come from carbon steel contamination, such as filings from cutting or grinding nearby, or from the wrong grade for very harsh spots like seafront wharves. For coastal work, ask us before you order.
Stainless machine screws can gall (lock up in the thread) if driven too fast or overtightened. Drive them at a slower speed, and lubricate the thread with a molybdenum disulphide based lubricant where you can.
Fitting security screws
- Choose the drive and order the matching bit or key with the screws.
- For self-tapping screws, drill a pilot hole to suit the screw and material.
- Seat the bit fully in the recess and keep it in line with the screw, so the pin or eyes are not damaged.
- Drive at a steady, moderate speed and stop when the head is snug. Do not overtighten.
- Keep the bit somewhere safe: you will need it to remove the screw later. One-way screws are made to stay.
Security screws in Adelaide
Allmat supplies security screws and the bits to fit them to builders, councils, sign makers and trade across Adelaide and South Australia. Add the screws and bits to a quote with the rest of your list, and we will price the lot.
Security screws for number plates, signs and public places
Tamper proof security screws and the bits to fit them are available to order from Allmat for builders, councils, sign makers, maintenance crews and trade across Adelaide and South Australia. Order through Allmat, we pick and pack it, then click and collect from the Allmat yard or have it delivered to site.
Goes with
Questions
What are anti theft number plate screws?
Security screws used to fix a number plate (licence plate) so it cannot be removed without a special bit. Ours are 304 stainless with pin Torx, pin hex, snake-eye or one-way drives, in self-tapping and metric machine threads.
What size screws do I need for my number plate?
Match the screws already in the car. Check whether they are self-tapping screws or machine screws, then measure the diameter and length. We carry self-tapping security screws from #6 to #14 and metric machine screws from M3 to M12, sold in packs (mostly 100), with the bit sold separately. Call us on 1300 03 03 63 if you are unsure.
What bit do I need for a pin Torx security screw?
A security Torx bit with a hole for the pin, in the same T size. For our button head metric screws: M3 T10, M4 T20, M5 T25, M6 T30, M8 T40, M10 T45, M12 T50. The full list is in the size table.
How do you remove a security screw?
With the matching security bit: a pin Torx or pin hex bit with a centre hole, or a two-pin eye drive bit for snake-eye screws. One-way screws are made not to come out, so use them only where the screw is permanent.
Are tamper proof and tamper resistant screws the same?
Yes, both names describe security screws with a drive that ordinary tools cannot turn. They stop casual tampering and theft; anyone with the matching bit can still remove them, which is why you keep the bits secure.
Are your security screws stainless steel?
Yes, all of them are 304 (A2) stainless steel.
Where can I buy security screws in Adelaide?
Order through Allmat. Order ahead by phone on 1300 03 03 63 or send your list for a quote, then click and collect from 25 Kapara Road, Gillman, or have them delivered to site.
Security / Tamper-Resistant Screw: sizes and finishes we supply
283 lines by type and finish. Pick one above for its product code and pack sizes.
| Head | Finish | Sizes | Lengths | Lines |
|---|---|---|---|---|
| Countersunk | 304 Stainless | M3, M4, M5, M6, M8 | 6 to 80 (16 lengths) | 88 |
| Button | 304 Stainless | M3, M4, M5, M6, M8, M10, M12 | 6 to 80 (15 lengths) | 83 |
| Countersunk | 304 Stainless | #6, #8, #10, #14 | 1/2, 5/8, 3/4, 1, 1-1/4, 1-1/2 inch | 40 |
| Pan | 304 Stainless | #6, #8, #10, #14 | 3/8, 1/2, 5/8, 3/4, 1, 1-1/2, 2 inch | 21 |
| Pan | 304 Stainless | M4, M5, M6 | 10, 12, 16, 20, 25, 30, 40 | 16 |
| Button | 304 Stainless | #6, #8, #10, #14 | 1/2, 3/4, 1, 1-1/4, 1-1/2 inch | 16 |
| Button | 304 Stainless | 3/8 | 15 to 82mm (11 lengths) | 11 |
| Raised csk | 304 Stainless | #8, #10 | 1/2, 3/4, 1, 1-1/2 inch | 8 |
Data sheets and documents
The documents for the product you choose are listed with the selector above. Here is every Security / Tamper-Resistant Screw document from Hobson Engineering.
All Security / Tamper-Resistant Screw documents (6)
Data sheets and technical data (1)
Did You Know flyers (3)
Guides and articles (2)
Need them in bulk?
Add the sizes you need to your quote, or send us your list and we’ll price the lot and supply it with the rest of your order.
Browse all security screws