Drive & Security Screw Identification
What’s the recess in that screw head — and what bit does it take? Match the shape below, including the tamper-resistant ones that need a special driver.
The drive is the shape cut into the screw head — it decides which bit or driver fits. Match the recess to the pictures below. Using the wrong one (a Phillips bit in a Pozidriv head is the classic) cams out and chews up the head:
Common drives
Slotted
A single straight slot. The original — a flat-blade driver.
Phillips
A cross with tapered ends. The everyday cross-head; a “PH” bit.
Pozidriv
Like Phillips but with four extra fine lines. Needs a PZ bit, not PH.
Square (Robertson)
A square socket. Grips hard and resists cam-out.
Torx (star)
A six-point star. Common on decking, electronics, automotive. A “T” bit.
Hex (Allen)
A six-sided socket. Takes a hex key / Allen wrench.
Combination
Slotted and Phillips in one head — driven by either.
The Phillips vs. Pozidriv trap
They look nearly identical, but a Phillips bit in a Pozidriv screw (or vice-versa) cams out and rounds the head. Pozidriv has four faint extra lines between the cross arms — if you see them, reach for a PZ bit.
Security / tamper-resistant drives
Pin-in Torx
Torx with a pin in the center — a standard bit won’t seat. Needs a security Torx bit.
Pin-in hex
Hex socket with a center pin. Needs a security (hollow) hex key.
Spanner (snake-eye)
Two round holes. Driven only by a matching two-pin spanner bit.
Tri-wing
Three angled slots from the center. Aerospace and electronics; a tri-wing bit.
Torq-set
An offset cross — looks like Phillips but the arms are stepped. Needs a torq-set bit.
One-way (clutch)
A slot that drives in but not out — a flat driver slips on removal. Install-only by design.
If you’re stuck
Stripped a head? That’s often a wrong-bit story — the right driver and a fresh screw usually beat fighting a chewed-up one.