The M1126 Stryker is a beautifully designed vehicle. It's packed with 16.5 tons of high-hardness steel to shield the passengers from direct attacks and a unique underbelly design to help defend against IEDs. Many are outfitted with remote weapon systems, allowing troops to engage the enemy without fear of snipers. It even has one of the most state-of-the-art fire-extinguishing systems in the world in case the worst happens.
With all that protection, it seems strange that someone decided a bunch of steel bars around it would make great armor...
Though it might look flimsy, the simple fence design is an excellent counter considering how explosives blow up. Having thick, reactive armor works wonders against conventional fragmentation rounds, but HEAT (High explosive, anti-tank) rounds are designed specifically to burst through it.
Take a standard RPG-7 single-stage HEAT round for instance: The explosion isn't what makes it deadly. By forcing the explosion into a narrow cone, it's used to blow a hole through whatever it hits. It's the molten copper follows and uses the pathway cleared by the explosion that's truly deadly.
Not pleasant, to say the least. (Image via GIPHY)In comes what we've been calling "fence armor." This type of armor is actually called "slat armor" and has been used since the World War II on German panzers. The Germans needed an extra layer of defense from Russian anti-tank rifles and low velocity, high explosive rounds. They added steel plates. set a few inches away from the actual shell of the vehicle, so when it's hit, the cheaper plates would be hit and the copper would have time to cool, causing minimal damage.
This method of stopping common HEAT rounds is still used today by armies going against enemies with RPGs. While slat armor isn't 100% effective (no armor is, truly), it does have up to 70% effectiveness, which is remarkable for a solution that costs nearly nothing, is an addition to existing armor, and doesn't negatively affect the mission.
Though nowhere near as effective, even ISIS tried to Mad Max their vehicles. Note, for this to work, slat armor needs to be a few inches away from the vehicle, it should cover vital spots, and shouldn't be welded on (since the point of it is to be destroyed and swapped out).