Security screw, also known as tamper proof screws, are a type of standard screw that has a unique head design that makes it nearly impossible to remove or tamper with. They are used to add an extra level of security in applications where it is important to protect against unauthorized access, removal, or vandalism. Security screws have a different drive style than conventional screws, and they typically require a specific tool to install and remove them. Security screws are a great choice for situations where unauthorized tampering can lead to system failure, increased costs of operation and maintenance, new materials required, or increased operating time, among other things.

Security screws are available in a wide variety of head styles, sizes and thread types, as well as material grades and finishes. They can be used to fasten just about anything from doors and cabinets, to electrical and electronic equipment, to automotive components and systems. Some of the most popular types of security screws are hex pin style, Torx (trademark for a specific 6-lobe recess), pin Torx head, and one-way screws.

A hex pin style security screw has an internal pin within the hexagonal socket of its head, making it difficult to remove or tamper with. It requires a special insert bit or key wrench to be installed or removed, which helps deter theft and tampering by keeping tools off the premises and out of reach. Hex pin security screws are suitable for medium torque applications.

Another popular security screw is the Torx (trademark for a specific six-lobe recess) head, which also needs a special driver to be installed or removed. Its head has a star shape with a central pin, which prevents it from being removed with a regular Torx screwdriver. It is commonly used in high-security environments, such as computer hardware, automobiles and airplanes, to help protect against tampering and theft.

Other security screws have a square drive, which is a square-shaped recess that allows it to be removed with a standard Phillips screwdriver. These types of security screws are not as common, but they can be useful in some applications where it is important to protect against tampering or theft.

There are many other types of security screws, including one-way screws that have a section of their heads that curves away from the section that a screwdriver would be inserted into to prevent it from gripping the head. Tamper-resistant screws have a reverse thread that tightens if someone tries to remove them counterclockwise. There are also anti-tamper screws that have a low-profile truss head and a Tri-Wing drive. Some of these screws can be installed only with a special tool, such as an insert tool or key wrench, and are often used in applications that are susceptible to tampering or vandalism, such as vehicle engines, braking systems for bicycles, and consumer electronics.