Just going for a jog along city streets already felt vulnerable for a lot of women. Then two joggers were murdered recently, one in NYC and the other in Massachusetts, prompting many nervous runners in the metro area to respond by purchasing bras that conceal weapons.

The aptly-named Booby Trap bras are not messing around.

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Last Tuesday, 30-year-old Karina Vetrano went for a solo run in Howard Beach, N.Y. On Sunday, 27-year-old NYC resident Vanessa Marcotte went for an afternoon run while visiting family in Princeton, Mass. Both were found murdered. The killings, which police said may not be connected, have sparked fear among female joggers -- and an uptick in sales of Booby Trap bras.

The "Just in Case" Booby Trap bras contain a sheath in the center designed to hold either a small knife or container of pepper spray -- each sold separately. The bras, made from a poly blend called Supplex, are about $50 for the pepper spray version or about $54 for the knife one, reports NBC New York. Both pockets are constructed from Neoprene, although the knife version also contains a magnet to hold the weapon in place.

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Company founder Jennifer Cutrona explained online that she created the bra after being jumped while running on a trail. "The little pocket knives I had collected over the years were all at home in the drawer with my pepper spray," she wrote. Although she got away from the guy, the experience changed her perspective.

"I needed something I could pull in less than a second," she wrote. This week Cutrona told the New York Post that sales of her bras "are blowing up."

The small curved knife that fits inside the bra costs about $13 and has holes so it can be slipped over a finger for grip. Cutrona recognizes that an attacker could use the knife against the wearer, telling the Post that she recommends practicing with it 50 times before donning the weapon. (The company also makes a unisex pocket sleeve.)

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Currently she's partnering with Mace to develop a bra with a built-in 911 call button that she expects will be available from her Texas-based company by December.

Meanwhile, police are urging residents near the areas where the murdered women were found to be careful and vigilant. For some that means skipping the headphones, carrying trackers and running in groups.

The Booby Trap Bras motto: Stay safe, stay active. Mine: Stay sharp.

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