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LONDON — There's the dispatch box in Westminster's Houses of Parliament from which Prime Minister Theresa May sets out her government's policy and the ballot box through which Britons voted on June 23, 2016 to leave the European Union. Now, some in the U.K. are turning to so-called "Brexit Boxes."

With the deadline to leave the European Union rapidly approaching, the prospect of crashing out without a deal has some Britons taking an approach akin to preparing for a natural disaster.

From the outside, it looks like any other white cardboard box.

It’s inside the box that things start to get interesting: there’s fire starter gel, a water filter, and a whole month’s worth of freeze dried meals — in flavors like chicken tikka and mac & cheese.

It’s basically everything you would need to survive the apocalypse. Or — maybe — a hard Brexit.

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A "Brexit Box" containing dried food and other supplies. Ziad Jaber / NBC News

The company that makes the kits, Emergency Food Storage in the Northern England town of Leeds, describes them as “Brexit stockpiling made easy.”

The Brexit Box doesn’t come cheap, at close to $400 for about 100 meals. But owner James Blake told NBC News that he's sold more than 600 boxes, with sales up more than 20 percent since December.

Britain is set to leave the E.U. on March 29th, and with parliament struggling to agree on a deal, the possibility of a "no-deal" Brexit is still very much on the table.

Experts have warned that if Britain leaves the E.U. without a deal in place to govern their future relationship with the bloc, there could be chaos at the border, leading to possible shortages of food and medicine.

Earlier this week, the heads of major U.K. supermarket and food chains sent a letter to MPs warning of “significant disruption” if that came to pass, with nearly one third of the food consumed in the country coming from the European Union.

“Our ability to mitigate these risks is limited. As prudent businesses we are stockpiling where possible, but all frozen and chilled storage is already being used and there is very little general warehousing space available in the U.K.,” the letter read. “We anticipate significant risks to maintaining the choice, quality and durability of food that our customers have come to expect in our stores, and there will be inevitable pressure on food prices from higher transport costs, currency devaluation and tariffs.”

The government recently stepped up its own preparations, with around 3,500 troops set to be on standby to help with any disruptions. But some have chosen to take matters into their own hands.

In a Facebook group called "48% Preppers” — a reference to the 48 percent of the country that voted to Remain in the E.U. — people trade tips and discuss the practical preparations they are making for Brexit.

Across social media Britons have been sharing anecdotal tales of stocking up on non-perishable items from supermarkets.

As the deadline looms, many may feel their best bet is to keep calm and carry on — but prepare for the worst.