M1 M1.2 Stainless Steel Five-Star Pentalobe Machine Screws — Micro Threaded Fasteners

M1 refers to a 1mm nominal thread diameter and M1.2 refers to a 1.2mm nominal thread diameter. Always match the screw to your existing tapped hole. The safest method is to measure the original screw shank with a caliper or consult the device service manual. M1 is commonly found in the smallest smartphones and wearables; M1.2 appears in slightly larger compact electronics. Quick reference: M1×4mm has a 4mm shank (≈ 5/32"); M1.2×1.4mm has a 1.4mm shank (≈ 1/16").

Stainless steel micro screws in the M1–M1.2 range generally have a tensile strength in the range of 500–700 MPa depending on the alloy grade. They are well-suited for securing lightweight panels, PCBs, and precision device housings where clamping force requirements are low and corrosion resistance matters more than raw strength.

Stainless steel is naturally corrosion-resistant and generally performs well in humid, moist, and mildly corrosive environments. These micro screws are suitable for indoor electronics and light outdoor applications. For fully submerged or saltwater environments, a marine-grade stainless alloy is typically a better long-term choice.

These screws follow the ISO metric thread standard. M1 has a standard pitch of 0.25mm and M1.2 has a standard pitch of 0.25mm. They are compatible with standard metric tapped holes and threaded inserts of the same designation used in precision electronics, watchmaking, and optical instruments.

You need a dedicated pentalobe (five-point star) screwdriver — not a Phillips, Torx, or flathead driver. For M1–M1.2 screws, a P2 or P5 pentalobe bit is typically the correct fit depending on the exact head size. Using the wrong driver will strip the delicate five-star recess. Always test-fit the bit before applying torque.

Both are multi-point star drives, but they are not interchangeable. Torx has six points with straight-sided lobes, while pentalobe has five points with rounded, flower-shaped lobes. A Torx bit used on a pentalobe screw will damage the recess. Always use a dedicated pentalobe driver for these screws.

For replacement screws, measure the original with a caliper. The length listed (e.g., 4mm for M1×4mm) refers to the full shank length excluding the head. As a general rule, the screw should engage at least 1.5× its diameter of thread depth in the receiving material — for M1 screws, that means at least 1.5mm of thread engagement. For M1.2×1.4mm screws, the very short shank is designed for thin-panel or surface-mount applications.