Kate Middleton reportedly loves to wear high heels. And it turns out the Duchess of Cambridge has a secret weapon for how she can stand all day in her L.K. Bennett "Sledge" pumps: She gets help from Alice Bow insoles.

Earlier this week, a source told Us Weekly that Kate recently bought several pairs of the Alice Bow insoles at a Selfridges department store in London. “She picked up versions of the insole for both flat shoes and heels in an assortment of colors." The source added, "The Duchess is a fan of the brand."

The insoles would seem to explain how the Duchess is able to wear high heels wherever she goes. Even while pregnant with Princess Charlotte, Kate wore her favorite pumps.  She was even spotted wearing four-inch heels during her trip to New York City last December, reported the New York Daily News. Kate was five months pregnant then.

What could be special about these insoles? According to the London brand, each insole is designed to cushion the ball of the foot, and boasts high-quality padding wrapped in premium Italian leather. There are stickies on the back of each insole to hold it in place, if needed, plus, they're shaped to be worn with open-toed shoes as well.

But this latest fashion accessory update might have other effects beyond keeping the Duchess comfortable. Over the years, Kate has sparked a phenomenon called “the Kate effect,” wherein products she’s seen wearing or buying, either for herself or her children, end up becoming immensely popular. Marie Claire wrote that “the Kate effect” leads to an instant sell-out of any item she wears.

It seems getting the Duchess’ “seal of approval” is the ultimate honor for any fashion brand. The impact of Kate’s endorsement is even known to launch tiny labels into fully fledged companies. This could be the case for Alice Bow, which at the moment is experiencing a “delightfully unexpected volume of orders,” as stated on the company’s website.