Screw Drive Style

  • Bristol

    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

    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.

  • Phillips
Slotted

    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

    Cross drives are used with either a standard slotted driver. The drive style is designed in case of stripping one slot, the other slot can be used. These screws are often used to attach knobs to furniture.

  • Double
Hex

    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

    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

    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

    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

    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

    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

    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

    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

    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

    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

    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

    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.

  • Posidriv

    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

    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

    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

    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

    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.

  • Drilled
Spanner

    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.

  • One
Way

    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.

  • Pin-in-head
Hex

    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.

  • Pin-in-Star

    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.

  • Tri-groove

    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

    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

    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

    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

    Uni-drive drives have a series of stacked hexagons, 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.