Elon Musk has sold $10M worth of flamethrowers since Sunday

Elon Musk

Tech entrepreneur Elon Musk says he has sold out a stock of 20,000 flamethrowers with a retail value of $10 million through The Boring Company, his infrastructure firm.

Musk tweeted early Thursday that the company had sold its last remaining flamethrowers, just five days after they went on sale. The flamethrowers are listed at $500 each, plus tax, on The Boring Company’s website, which says they will ship in the spring with a “complimentary Boring fire extinguisher." Musk said each flamethrower will be engraved with a serial number from 1 to 20,000.

“The rumor that I’m secretly creating a zombie apocalypse to generate demand for flamethrowers is completely false,” Musk joked on Twitter.

The company’s website lists the fire extinguisher at $30 per unit. The extinguisher “comes with a cool sticker,” according to the product listing.

Musk, 46, is best known as co-founder of the electric car company Tesla and aerospace company SpaceX. He posted a video of himself using one of the flamethrowers on his Instagram account over the weekend.

Musk promised to sell the flamethrowers if the Boring Company sold 50,000 branded hats, the Verge reported.

“Obviously, a flamethrower is a super terrible idea. Definitely don’t buy one,” Musk wrote on Twitter. “Unless you like fun.”

This story has been updated.