A Security screw is a fastener that has been engineered to be tough to undo or remove without the right tools. They can be found in industries that have high concerns for vandalism or opportunistic theft like banks, prisons and airports. But what exactly makes a security screw so tough? They can vary in their head design, lengths, thread design and materials. Some are bright zinc plated, while others are made from stainless steel and other alloys to resist corrosion.

In addition to the patented design that provides a tight tolerance between bit and screw for a "stick-fit" (and thus no loosening), a security screw can also be designed with a unique drive type. These are typically less common amongst members of the general public and therefore harder to find, which in turn offers a level of added security for the user.

There are various different levels of security available for a Security screw depending on the needs of the industry. Some are simple enough to deter casual or opportunistic interference while others are next to impossible to remove without a specific driver. This is why you'll often find them used in permanent fixings, rather than those that require regular maintenance like a kids playground.

A specialised security screw can also be hard to damage with commonly-available tools such as slotted or Phillips screwdrivers. This is because they're designed with smoothed heads that don't have any sharp edges. This can help avoid slipping out of a driver's socket and potentially damaging the tool.

In terms of sizing, security screws are usually available in both imperial and metric. However, this doesn't necessarily affect their head design or the way they're installed or removed as each has its own method of driving. For example, a torx head is defined by the six-pointed indentation that resembles a star and provides compatible screwdrivers with more points of contact. This helps to limit camming out - where the screwdriver slips out of the indentation under torque pressure.

Regardless of the level of security required, choosing the correct screw or bolt for your project can make or break its functionality. Ultimately, you want a screw that's going to be reliable for as long as possible in order to minimise maintenance and repair costs.