Product Description
No.4 A2 Stainless Steel Countersunk Pozi Self-Tapping Screws
These No.4 countersunk self-tapping screws are manufactured from corrosion-resistant A2 stainless steel and feature a Pozi cross-recessed drive. They are designed to form their own mating thread when driven into a correctly sized pilot hole in sheet metal, plastics and other suitable materials.
The flat countersunk head sits flush with the surface when installed into a correctly prepared countersink, providing a clean, snag-free finish. A2 stainless steel makes these screws suitable for general engineering, automotive, maintenance and outdoor applications where improved corrosion resistance is required.
Key Features
- Nominal size: No.4 / approximately 2.9mm
- Available lengths: 1/4", 3/8", 1/2", 5/8", 3/4" and 1"
- Material: A2 austenitic stainless steel
- Head style: flat countersunk
- Drive: Pozi cross recess
- Thread type stated on the existing page: AB self-tapping thread
- Approximate head diameter: 5.5mm / 7/32"
- Legacy dimensional standard: DIN 7982
- Current dimensional standard: ISO 7050 / BS EN ISO 7050
Typical Applications
- Sheet-metal panels and enclosures
- Automotive trim and light fabrication
- Electrical and equipment housings
- Plastic components and covers
- Signs, brackets and fittings
- General maintenance and outdoor repairs
Installation Information
Use a correctly sized pilot hole for the material thickness and application. A hole that is too small can cause excessive installation torque or damage the screw, while an oversized hole may prevent the thread from forming securely.
Use the correct Pozi driver bit and maintain firm axial pressure during installation. Stainless steel fasteners should be driven at a controlled speed to reduce heat generation, drive damage and the risk of galling.
Applicable Standards
ISO 7050:2011 and its current British adoption, BS EN ISO 7050:2011, specify cross-recessed countersunk flat-head tapping screws in sizes from ST2.2 to ST9.5. The 2.9mm nominal diameter falls within this range.
DIN 7982 is the withdrawn legacy dimensional standard and has been superseded by DIN EN ISO 7050. For a genuine Pozi drive, the cross recess should be identified as type Z. Type H denotes a Phillips recess.
Mechanical properties for corrosion-resistant stainless steel tapping screws are covered by ISO 3506-4 and BS EN ISO 3506-4. Standards compliance should only be claimed after the dimensions, thread form, drive recess and mechanical properties have been verified.
Please note that specifications are provided as a guide. Confirm pilot-hole requirements, material thickness and critical dimensions before ordering.
Browse our complete range of countersunk Pozi self-tapping screws or view all self-tapping screws.
| A | B | C | D | E | F |
| No.4 | 2.9mm | 1" | 25mm | 7/32" | 5.5mm |
| No.4 | 2.9mm | 1/2" | 13mm | 7/32" | 5.5mm |
| No.4 | 2.9mm | 1/4" | 6mm | 7/32" | 5.5mm |
| No.4 | 2.9mm | 3/4" | 19mm | 7/32" | 5.5mm |
| No.4 | 2.9mm | 3/8" | 9.5mm | 7/32" | 5.5mm |
| No.4 | 2.9mm | 5/8" | 16mm | 7/32" | 5.5mm |
Please Note: Specifications given are intended as a guide only. If critical to your project please check with us first.
