ST. LOUIS —

One of the back-to-school items surging in popularity this year has nothing to do with education and everything to do with protection.

In light of recent school shootings, bulletproof backpacks have become a big seller, but do they work and are they necessary?

According to Google Trends, searches for bulletproof backpacks have soared twice in the last five years.

First, after the shooting at Marjory Stoneman Douglas High School in Parkland, Florida.

And second, in the days following the deadly mass shootings in El Paso, Texas, and Dayton, Ohio.

5 On Your Side tested the Guard Dog Proshield II backpack. It says "bulletproof" on the branding and label, but if you look at the fine print, it's only rated to stop handguns.

Aaron Tarlow, the owner of Southern Armory, provided the farm and the guns. We brought the backpack.

We started by firing a 9mm handgun. When we fired it, the bullet was stopped before it pierced the backplate.

"Actually it has got some of the trauma plating to it, too, which absorbs the impact," Tarlow said.

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The back of the backpack is essentially a Kevlar vest, similar to the kind police officers wear.

Like the vest, the whole goal is for the bullet to not make it through.

We also tested a .22 caliber handgun, a .45 caliber handgun and a .357 Magnum handgun.

The .22 and .45 didn't break through.

The .357 came close. You could see the bullet protruding through the back of the Kevlar portion, but all things considered, the backpack stopped it.

Those handgun rounds proved the backpack does exactly what it claims to do, but what if a gunman brings in a high-powered rifle?

We shot an AR-15 300 Blackout at the backpack. The backpack didn't even slow the bullet down.

"Yeah, you can even see where it went through the straps, too," Tarlow said.

It was the same result for the Daniel Defense Rifle, using .223 soft point rounds.

All three bullets went straight through.

Finally, we fired a hunting rifle, with the same result.

According to the U.S. Center for Homeland Defense and Security, more handguns have been used in school shootings than high-powered rifles, and for that reason, Tarlow said bulletproof backpacks might be worth considering.

"For what it is, yeah. For stopping handgun threats, absolutely," Tarlow said.

Doug Parisi, a school safety expert and consultant, sees it differently.

"I think parents probably should not be looking at this," Parisi said.

He believes using backpacks to stop bullets isn't effective for a couple of reasons. He said school shootings with the most deaths involved high-powered rifles.

"They don't stop rifle rounds," Parisi said.

He also argued the very concept of protection for a student's back doesn't match the evidence.

"That's not really the problem that we're having. We're not having the problem that students are being shot in the back as they're fleeing the school. These things are happening up close," he said.

Then, there's the price.

Bulletproof backpacks like the ProShield II run around $150.

If you want to buy a soft ballistic insert, which can make any backpack like the one we tested, they cost around $150, too.

It gets much more expensive from there.

Hard ballistic inserts, made out of polysilicon and steel, which can stand up to rifle rounds, run between $400-$500.

"You can still insert these into a backpack if you want rifle protection. It will also stop a handgun as well," said Aaron Tarlow, the owner of Southern Armory, who sells many of these products.

Parisi said even if parents are willing to spend big money, there are other ways to ensure their children are protected.

"What they should really be doing is focusing their attention towards what the school is doing to keep their kids safe," he said.

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One of Parisi's other concerns with the backpacks is that they only have a shelf life of about five years before they start to break down, much like a Kevlar vest.

He also said he's concerned with the message it sends to kids when they're sent to school with protective armor.

Some parents may argue that aspect alone does more harm than good.

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