Know the Difference: Flak Jackets, Kevlar & the Bulletproof Vest

Body armor is often categorized by many attributes, including function, brand, level of protection or sometimes even materials. So how do you begin your research for the best products? It can get overwhelming in a space where flak jackets, bulletproof vests and Kevlar seem to reign supreme in descriptions and articles. Let’s differentiate between materials, brand names and societal trends within the body armor space.

Kevlar — Material or Body Armor?

We’ll start with material. When researching body armor, Kevlar armor seems to pop up in most searches. It may surprise you to know that Kevlar itself is simply the registered trademark for a type of bullet or stab resistant para-aramid synthetic fiber. Kevlar fabric or fiber was developed at Dupont back in 1965 and has become commonplace in the body armor industry. It’s usually spun into ropes or fabric sheets that can be used on their own or as a component within a composite material. Kevlar has a high tensile strength-to-weight ratio making it five times stronger than steel and thus a great addition to most soft body protection products. It was first used commercially in the 70s as a replacement for steel in car racing tires, but eventually found its way into the body armor market. It has since become the most commonly used material in soft body armor.

Kevlar is not a standalone body armor product. You can purchase Kevlar fiber directly from Dupont. But in the body armor space, you’re more likely to find Kevlar acting as a component within a composite protective material. While technically a Kevlar vest isn’t an actual standalone product, Kevlar material is one of several options available that meets the soft body armor requirements NIJ has put in place.

Unlike a material element like Kevlar, flak and flak jackets have a different history and role in the body armor space.

What is a Flak Jacket?

Back in the 1860s, soldiers started adding steel in the pockets of military vests. During World War I, military officers pushed for more effective body armor to prevent additional casualties. It wasn’t actually until World War II that the term ‘flak jacket’ was first used. Flak jackets were developed to help protect aircrew from debris and shell fragments coming from German anti-aircraft guns. Pilots quickly realized that while conceptually helpful, the jackets were too big and bulky to fit in their small aircrafts and were thus handed over to the Air Force who adopted them as a protection standard. The first flak jackets manufactured weighed 22lbs, but dropped in weight as materials were replaced with other lightweight options.

Contrary to popular belief, flak jackets are not interchangeable with bulletproof vests. They are designed to protect against fragments from high explosive weaponry — like anti-aircraft guns, land mines, low velocity projectiles and grenades. Flak jackets were never designed or developed to provide protection against gunfire, though some can sustain the velocity of a bullet depending on the specific body armor and weapon. It was the armor developed in the 70s along with the invention of Kevlar that was ultimately incorporated into NIJ standards regarding bullet resistance.

The Bulletproof Vest

Before discussing the role of the bulletproof vest in today’s body armor industry, it’s important to understand that the term itself isn’t accurate. There is no body armor product on the market that can truly be considered ‘bulletproof.’ While body armor manufacturers do their best to anticipate special threats, there will always be a weapon, bullet or circumstance that can lead to bullet penetration. Though commonly known as bulletproof vests, we are actually referring to bullet-resistant vests per NIJ standards.

The idea of a military or police bulletproof vest is to absorb the impact and reduce or stop bullets or shrapnel penetration to the body. Soft bulletproof vests are made of dozens of layers of fibers that act as a barrier to different ammunition and guns. The material within these laminated fibers is often Kevlar. Soft body armor vests act as a first layer of protection and can be paired with trauma plates for additional protection against higher level threats. For example, Angel Armor’s RISE Body Armor vest on its own can meet either NIJ Level II or Level IIIA standards. When paired with Truth SNAP trauma plates, the system offers tiered protection up to NIJ Level III.

Bulletproof vests date back to the 1500s among Italian and Roman royalty. By the 1800s the Japanese were creating soft body armor using layers of silk. The US began to spend more time researching soft body armor options in the early 1900s, and the invention of the flak jacket helped lead the way to more advanced threat protection. It was the invention of Kevlar that really propelled the industry forward and led to the creation of the more modern bulletproof vests we see today.

While not a perfect comparison, Kevlar, flak jackets and bulletproof vests all play a role in the body armor industry. When looking for the right body armor products, consider the threats your team my face. And as always, refer to NIJ to ensure your selection meets the standards needed to offer the highest level of protection.