
Bristol
drives have four or six splines, which are sharp plateau-like
ridges
on the fastener and on the tool. Most of the turning force is applied at
right
angles to the fastener's spline faces, which reduces stripping the
fastener
head. These drives are often found in softer metals, such as brass.

Clutch
drives lock into the fastener head when the tool is turned
counterclockwise,
and unlock when the turning direction is reversed. Type A, sometimes
called a
standard clutch, is an older style. Newer type G drives are recommended
for
maintenance work, and other applications where the fastener must be
removed and
reset frequently.

Combination
Phillips-slotted drives are used with either a Phillips or
standard
slotted driver. The drive style is designed so that the driver will cam
out, or
slip out, under pressure to prevent over-tightening. These screws are
often
used to attach knobs to furniture.

Cross
drives are used with either a Phillips or standard slotted
driver.
The drive style is designed so that the driver will cam out, or slip
out, under
pressure to prevent over-tightening. These screws are often used to
attach
knobs to furniture.

Double hex
drives have a 12-point socket shaped like two hexes, which are
rotated and overlaid upon each other. Although double hex drives
resemble
triple square and spline drives, they are incompatible. Standard hex
keys may
be used with double hex sockets, but the near-circular shape decreases
torque
and increases stripping the fastener head.

External hex
drives are six-sided, or hexagonal, and are driven by a
crescent
wrench, combination wrench, or sockets. They require minimal clearance
above
the fastener because they can be tightened or loosened from the side.
External
hex drives outperform external square drives in scenarios with limited
fastener
access, because smaller swing arcs may be used to rotate the fastener.

External square
drives are four-sided, or square-shaped. They are driven by a
crescent wrench, open-ended wrench, or sockets. They require minimal
clearance
above the fastener because they can be tightened or loosened from the
side.
External square drives are less common than external hex drives. Square
fasteners are often found in plumbing, lighting equipment, and gate
hardware.

Frearson
drives, also known as Reed and Prince drives, have a
cross-shaped
slot like a Phillips drive. Unlike a Phillips drive, Frearson drives are
a
perfect cross shape, for greater torque and more cam out resistance.
These
drives also have a more pointed 75 degree internal V shape. One driver
or bit
fits all fastener sizes, an advantage over Phillips drives.
Unfortunately, it
is easy to confuse Frearson and Phillips drives, increasing the chance
that the
incorrect tool will be chosen, and increasing the chance of damage to
the
workpiece, fastener, or tool. These drives are often used in marine
hardware.

Internal hex
drives, also known as hex-socket drives, are similar to hex
drives,
but have a hexagonal hole in the center that requires an Allen key, also
known
as a hex key or Allen wrench.

Internal
square drives, also known as Robertson drives, have a
square-shaped
center. They require a special driver and are designed to maximize
torque. The
driver will not cam out, so the fastener does not have to be held in
place
during installation, leaving both hands free to drive the internal
square
fastener. These drives are commonly used in woodworking and carpentry.

JIS
drives, or Japanese Industrial System drives, are commonly
found in
Japanese electronics. They resemble the Phillips drive but are designed
to not
cam out, and may be damaged by a Phillips driver. Often, a single dot or
an X
mark near the cross-shaped slot identifies a JIS drive over a Frearson
or
Phillips drive.

Lobed
drives have an external six-sided star shape, which allows a
more
even spread of force on the fastener head, thereby helping to prevent
tool or
fastener damage. Torque transfer on a lobed fastener is greater than for
the
corresponding internal star. Lobed fasteners weigh approximately 20% to
40%
less than equivalent hex and pan head fasteners, which is advantageous
for
applications where weight may be a concern, such as automobile engines.

Not
applicable defines a fastener that is either hand-driven, or
held in
place during use. Hand driven examples include knurled screws and spade
screws.
Since these are head styles, the drive style is not applicable. Carriage
bolts,
eye bolts, J bolts, and U bolts are all held in place during use while
the nut
is fed onto the threaded end of the fastener, tightening the bolt in
place from
the end rather than the head. The carriage bolt is held by its square
neck,
while eye, J, and U bolts are held in place by hand or with a tool.

Pentagon
drives have five-sided fastener heads. The fastener is
sometimes
known as a penta head bolt or screw. Pentagon drives require a specific
tool
with a five-point socket. Utilities such as water meter covers, natural
gas
valves, fire hydrants, and electrical cabinets are commonly secured with
penta
fasteners. The non-standard shape offers a higher degree of security
over a hex
fastener, since tools that are commonly used with hexes, such as
crescent
wrenches, are not compatible with pentagon driven fasteners.

Phillips
drives have x-shaped slots with rounded corners and are driven
with a
Phillips screwdriver. The slot is designed so that the driver will
cam-out, or
slip out, under pressure to prevent
over-tightening.

Phillips-square
drives,
also known as Quadrex, are a combination of the Phillips and
internal square screw drives. These drives are less prone to cam out
than
either Phillips or square drives, allowing higher torque to be used.
While a
Phillips or a square tool may be used, a dedicated tool is available for
this
drive system that increases the surface area between the tool and the
fastener
so that additional torque can be applied.

Pozidriv
drives are an improved version of the Phillips drive, with
less
likelihood to cam out, allowing greater torque to be applied. Pozidriv
screwdrivers and screws can be distinguished from Phillips by the thin
markings
at 45 degrees from the cross. Pozidriv drives are visually very similar
to
Phillips, even with the distinguishing marks or ticks, so the drive
styles may
easily be confused. A Phillips driver will turn a Pozidriv fastener,
though
damage to the fastener may result. However, a Pozidriv driver will not
turn a
Phillips fastener. Pozidriv drives are sometimes confused with Supadriv
drives,
which are similar in appearance but a later development by the same
company.

Slotted
drives have a linear slot and are used with a flat-bladed
screwdriver. These drives are commonly used in woodworking and are prone
to
slippage.

Spline
drives have twelve splines, or rounded plateau-like ridges, on
the
fastener and tool. Spline drives resist cam out, so they are frequently
used in
high-torque applications, such as tamper-proof lug nuts.

Star
drives, also called Torx drives, have 6-pointed indentations
that
provide more driving surface area. These screws resist cam-out better
than
Phillips drives or slotted drives. They are used with a Torx
screwdriver.

Supadriv
drives are very similar in function and appearance to
Pozidriv, and
the two are often confused. Because the Supadriv drive is a later
development
by the same company, the same screwdriver heads may be used for both
types
without damage. The Supadriv drive allows for a small angular offset
between
the tool and fastener, while the Pozidriv drive must be directly in
line. The
Supadriv drive has two identification marks, or ticks, to the Pozidriv's
four.
When driving into a vertical surface, Supadriv outperforms Pozidriv by
reducing
cam out.

Tamper-resistant
drilled spanner drives have two holes opposite each other and
are
sometimes called snake eyes screws. Screws with tamper-resistant drives
require
special tools for removal and are used to discourage theft and
vandalism.

Tamper-resistant one
way drives have sloped slots, so the screw can be driven in
but the
driver slips out if you try to loosen the screw. Screws with
tamper-resistant
drives require special tools for removal and are used to discourage
theft and
vandalism.

Tamper-resistant
pin-in-head hex drives have a hexagonal shaped drive with a
pin in
the center. Screws with tamper-resistant drives require
special tools
for removal and are used to discourage theft and vandalism.

Tamper-resistant
pin-in-star
drives have a star-shaped hole with a pin in the center
and cannot be removed with a standard torx screwdriver. Screws with
tamper-resistant
drives require special tools for removal and are used to discourage
theft and
vandalism.

Tamper-resistant
tri-groove
drives have slots in the outer edge of the head which
provide driving force with a lowered risk of fastener damage and
failure.
Machine tools can be used with this driver socket, making this drive
suitable
for use where security and fast assembly are required, such as in the
mass
production of electronics.

Torq-set
drives are used in high-torque applications where breakage is a
concern, such as aerospace manufacturing. The Torq-set head is similar
in
appearance to a Phillips drive, as both have a cross-shaped slot with
four arms,
although the Torq-set cross arms are offset from each other. Because of
this,
neither a Phillips nor a flathead tool will fit a Torq-set fastener.

Tri-wing
drives, also known as triangular slotted drives, drives have
three
radial slots extending from the center of the fastener head, positioned
at 120
degrees to each other. Tri-wing fasteners may or may not include a small
triangular hole in the center of the three wings. The same driver may be
used
for both types. These fasteners are most commonly found on electronics
equipment, such as game consoles.

Triple square
drives, also known as XZN, drives have 12 equally spaced tips,
each
with an internal 90 degree angle. Three identical overlaid squares are
rotated
to form a pattern. Triple square drives are useful in higher torque
applications, such as drive train components. Many German vehicle
manufacturers
use triple square fasteners on their automobiles.

Uni-drive
drives have a series of stacked pentagons, as a socket in the
fastener and as a pyramid-like shape for the driver, that are intended
to
reduce delay by using one driver for all fasteners. The driver fits 1/2"
to 1" (M12 to M24) fasteners, lowering the overall need to change bits.
Uni-drive drives offer additional torque and less cam out when compared
to a
Philips head fastener, due to the additional points of contact between
driver
and fastener.