Simpson #12 x 2-1/2" Self-Drilling Flat-Head Screw with Wing in 410 Stainless Steel is a precision-engineered fastener from Simpson designed for attaching wood, plywood, and fiber cement to steel substrates up to 0.209" thick. The winged drill point bores a clean clearance hole through the wood layer so the workpiece stays flush against the steel rather than riding up the shank - then the wings snap off cleanly as the point contacts the steel, letting the machine threads engage firmly. The result is a tight, countersunk connection that would otherwise require pre-drilling, saving time and reducing steps on the job site.

Key Features

• Type 410 stainless steel construction with additional corrosion protection coating - provides durability in demanding environments while retaining the hardness needed to drill through metal, a combination that Type 316 stainless cannot offer due to its softer temper
• Winged drill point (Point Size 3) - wings bore a clearance hole through wood or fiber cement so the workpiece seats flush against the steel substrate rather than climbing the shank, then break off cleanly as the point engages the steel
• Flat countersunk head (0.380" diameter) with self-countersinking nibs - sits flush with the surface automatically without requiring a separate countersinking step, producing a clean, professional finish
• #3 square drive - delivers superior torque transfer compared to Phillips drives, reducing cam-out and driver slippage for faster, more controlled installation
• Full-length machine screw thread at 24 TPI - threaded from tip to head for maximum engagement in steel and a secure, vibration-resistant connection
• Shank slot design - enhances thread formation as the screw enters the steel and channels exhaust material away, reducing heat buildup and improving pull-out resistance
• 2-1/2" length - sized specifically for attaching 2x dimensional lumber to steel framing, with 2.375" maximum grip length to accommodate typical applications

Why This Product

• Eliminates pre-drilling into wood - the winged point does the clearance boring automatically, so installers driving wood or fiber cement into steel framing work faster with fewer tools in hand
• 410 stainless steel with heat-treatment hardening gives this screw the ability to penetrate steel up to 0.209" thick - a capability standard stainless fasteners lack - making it a practical choice where both drill performance and corrosion resistance are required
• The self-countersinking flat head with nibs means no separate countersink bit is needed; the screw seats itself flush in a single driving operation, reducing installation time on wood, plywood, and fiber cement panel work
• The #3 square drive and replacement bit compatibility (bit model BIT3S-2-R2) make it easy to keep the right driver on hand, reducing downtime from stripped or mismatched drive bits during production framing or panel installation

Specifications

• Brand: Simpson Strong-Tie
• Screw Size: #12
• Length: 2-1/2"
• Head Type: Flat Head
• Head Diameter: 0.380"
• Drive Type: #3 Square
• Shank Type: Shank Slot
• Thread Type: Machine Threads
• Thread Length: Full
• TPI: 24
• Max. Grip Length: 2.375"
• Point Type: Drill Point with Wings
• Point Size: 3
• Material: Type 410 Stainless Steel
• Max. Steel Substrate Thickness: 0.209"
• Country of Origin: Taiwan

Available Pack Options

• F12C250FDC: 100 Pk
• F12C250FDM: 1000 Pk
• F12C250FDB: 1800 Pk

Approved Applications

• Securing 2x dimensional lumber to steel framing
• Attaching plywood to steel substrate panels up to 0.209" thick
• Fastening fiber cement board to steel framing members
• Applications requiring a flush countersunk fastener in wood-to-steel connections

Frequently Asked Questions

What is the maximum steel thickness this screw can drill through?

This screw is rated for use with steel substrates up to 0.209" thick. The Type 410 stainless steel material can be hardened through heat treatment, giving it the strength to self-drill through steel - something standard stainless alloys are not designed to do.

How do the wings on the drill point work?

The wings sit just above the drill point and are sized larger than the screw shank. As the screw drives through wood or fiber cement, the wings bore a clearance hole slightly wider than the shank so the wood layer does not bind or climb up the threads. Once the point contacts the steel substrate, the wings break off cleanly and the machine threads engage the steel to pull the materials tightly together.

What driver bit does this screw require?

This screw uses a #3 square (Robertson-style) drive. The compatible replacement driver bit is model BIT3S-2-R2. The square drive geometry provides excellent torque transfer and reduces cam-out compared to Phillips drive patterns, which is particularly useful when driving into steel.

Is the 2-1/2" length the right size for my application?

The 2-1/2" length with a maximum grip length of 2.375" is designed for attaching 2x dimensional lumber to steel. For thinner material - such as 1" or 5/4" boards - the 2" length variant is the appropriate choice. Select the length based on the total thickness of the wood layer being fastened to the steel substrate.

Note: Product dimensions and/or thread length may differ from picture.