What is the difference between PH and PZ?

Recess geometry. PZ screws carry extra tick marks beside the cross and the bit seats over a wider face. A PH bit in a PZ screw cams out and rounds the recess; the two do not interchange.

How do impact bits differ from standard ones?

They are designed for the sudden torque of an impact driver: the shank twists in a controlled way to absorb energy, so the bit flexes rather than snapping. Standard bits fail quickly in an impact driver.

Why do my bits round off so fast?

Usually the wrong type or size (PH1 instead of PH2), working off the screw axis, or standard bits used in an impact driver.

How do I choose bit length?

25 mm is the standard and covers most work. 50-150 mm bits reach into deep or awkward places but flex more; the shortest bit that reaches gives the best control.

Do I need a magnetic holder?

It helps a great deal when working one-handed: it holds the screw on the bit. Magnetic holders also stiffen the bit and reduce wobble.

What does S2 steel mean?

It is the hard tool steel used for bits. A hard bit transmits torque without rounding the screw recess; a soft one destroys itself first and the screw head next.

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Driver Bits

The driver bit transmits torque into the screw head and is the fastest-wearing part in the chain; with the wrong type or size, both bit and screw head are ruined. This page covers the types, what impact rating changes, and choosing a holder. The catalogue holds over 290 products.

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Types and sizes

Bit type follows the recess in the screw head. PH (Phillips) and PZ (Pozidriv) look alike but differ: PZ screws carry extra tick marks, and a PH bit in a PZ screw cams out and ruins the recess.

Type	Description	Where
PH (Phillips)	Cross, tapered recess	General assembly, wood screws
PZ (Pozidriv)	Cross plus tick marks	Furniture, plasterboard, chipboard screws
TX (Torx)	Six-point star	High torque, structural work
Slotted	Single slot	Electrical, older fixings
Hex	Internal hexagon	Furniture, machine bolts
Square (Robertson)	Square recess	Imported wood screws

Impact rating and S2 steel

Standard bits break in an impact driver: hammer torque loads them suddenly. Impact rated bits are designed for it — the shank twists in a controlled way and absorbs the energy, so the bit flexes rather than snaps.

The steel is usually S2: hard enough to transmit torque without rounding the screw recess. Coated bits (torsion zones, diamond dust) add life and grip.

Use only impact rated bits in an impact driver.
Never put a PH bit in a PZ screw — it will cam out.
A magnetic holder stops long bits dropping the screw.
A worn bit ruins screws too — replace it.

Frequently Asked Questions

What is the difference between PH and PZ?
Recess geometry. PZ screws carry extra tick marks beside the cross and the bit seats over a wider face. A PH bit in a PZ screw cams out and rounds the recess; the two do not interchange.
How do impact bits differ from standard ones?
They are designed for the sudden torque of an impact driver: the shank twists in a controlled way to absorb energy, so the bit flexes rather than snapping. Standard bits fail quickly in an impact driver.
Why do my bits round off so fast?
Usually the wrong type or size (PH1 instead of PH2), working off the screw axis, or standard bits used in an impact driver.
How do I choose bit length?
25 mm is the standard and covers most work. 50-150 mm bits reach into deep or awkward places but flex more; the shortest bit that reaches gives the best control.
Do I need a magnetic holder?
It helps a great deal when working one-handed: it holds the screw on the bit. Magnetic holders also stiffen the bit and reduce wobble.
What does S2 steel mean?
It is the hard tool steel used for bits. A hard bit transmits torque without rounding the screw recess; a soft one destroys itself first and the screw head next.