The Malco Zip-In Self-Piercing Screws, model HW12X2, bring fast, reliable fastening to thin sheet metal jobs with a single streamlined step. These 5/16 in. slotted hex washer head screws are zinc plated for durability and corrosion resistance, designed to zip through metal without the need for pre-drilling. Packaged in practical quantities, they’re ready for larger projects or ongoing work on ductwork, roofing, or sign fabrication.

What makes these screws stand out

• Self-piercing design eliminates the need for pilot holes on thin-gauge sheet metal, speeding up installations and reducing tool wear.
• 5/16" slotted hex washer head provides a secure seating surface with ample bearing area, while the washer helps seal and distribute load to resist pull-out.
• Type A single thread is optimized for metal-to-metal fastening, delivering clean, fast cutting and strong clamping in one motion.
• Zinc plating offers improved corrosion resistance for longer service life in exposed or humid environments.
• Flexible options—longer lengths and multi-piece quantities are available to fit a wide range of applications, including the 1800-piece packs referenced in the product title.

Ideal uses and scenarios

• HVAC ductwork assemblies and metal enclosure builds where quick, reliable fastening is essential.
• Thin-gauge roofing, siding, and flashing installations where a clean finish and strong hold matter most.
• Sign mounting, metal framing, and lightweight automotive body repairs that require a dependable, easy-to-drive fastener.
• Any project that benefits from a fast, pre-drilled-free installation with a sealed washer under the head.

How to use

1. Align workpieces and position the screw where you need fastenings to occur.
2. Use a compatible hex driver to drive the screw; the self-piercing tip will begin cutting through the metal as you apply steady pressure.
3. Drive until the washer seats flush and the head sits evenly; avoid excessive torque to prevent damage to the washer or material.
4. For thicker assemblies, consider using a longer length option from the available selection to ensure full engagement.

Specifications at a glance

• Head and drive: 5/16" slotted hex washer head
• Thread style: Type A single thread
• Material finish: Zinc plated for corrosion resistance
• Package options: Longer lengths and multi-piece quantities available, including 1800-piece packs
• Application: Self-piercing sheet metal screws suitable for metal-to-metal joins