On the heels of the deadly shooting tragedy in Connecticut, parents' anxiety is driving a surge in sales of bullet-proof backpacks, in the hope the armored bags can give their kids a safety edge.

For under $300, the company Amendment II -- a play on the Second Amendment to the US constitution, which guarantees the right to bear arms -- is selling a boys' pack with Avengers characters on it and a Little Mermaid one for girls.

"Sewn into the rear of the pack, you can always be confident that the armor hasn't been accidentally left at home and that you or your child are protected in case of the unthinkable," the company says.

"It is an awful thing -- you would never imagine your child with this kind of stuff -- but since the Newtown tragedy, our sales are more than 10 times better than usual," said Richard Craig, head of the Utah company.

He refused to give precise sales figures, and his company also makes a less-costly bulletproof insert.

Amendment II is among a handful of companies that have seized the moment to offer protective gear for US schoolchildren whose parents arguably feel more vulnerable than ever.

Another company, BulletBlocker, is offering inserts for $150-200 that slip into a backpack like a book -- but with a different purpose.

"Light, easy to use, it is as big as a book" says Elmar Uy, vice president at the New Hampshire company.

He said that since Friday, sales were up by 40 percent to 40 inserts a day.

"We don't guarantee anything," he stressed. "It is just peace of mind, security for parents."

In last week's shooting in Newtown, Connecticut, a disturbed 20-year-old shot his mother, then 20 first graders and six staff at Sandy Hook Elementary School, before taking his own life.

"It is non-stop since Sandy Hook. It is all about the terrible things that happened last week, the end of the world hysteria, the Maya prediction; there is a lot of political uncertainty," said Devin Standard. His company Black Dragon Tactical has been selling 30 "ballistic panels" a day.

"The question is: is your life worth 229 dollars? Most people, when they think about this, they say yes," he added.

"If you have a car, you have car insurance; if you have a house, you have home insurance," he argued. "It is a little security blanket, it weighs almost nothing. But it is always there, just in case you are at the wrong place one day."