Following its release in March of the world’s first commercially available product made from manmade spider silk—a a line of snazzy neckties—California’s Bolt Threads is ready for its encore. Developed with Best Made Co., an outdoor-lifestyle brand that the technology firm unexpectedly acquired in July, the limited-edition Microsilk Cap of Courage marries Wyoming-milled Rambouillet wool with Bolt Threads’ signature yeast-derived bioengineered silk.

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Despite the eye-watering price of $198, a limited-edition run of 100 hats sold out in a matter of hours on Thursday.

Spider silk is one of Earth’s most valued textiles: It’s five times stronger than steel and thrice as tough as nylon or Kevlar, yet only a fraction of the width of human hair. Because spiders are territorial and cannibalistic, however, farming the fiber in significant quantities has been next to impossible.

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Related: First spider-silk garment to hit the market is this necktie from Bolt Threads

Enter Bolt Threads. Through its proprietary technology, which leverages proteins derived from yeast to replicate spider silk’s famous tensile strength and pliability, the company has been able to “tune” its Microsilk to deliver any combination of softness, strength, and durability. The fibers are even machine-washable, which gives them a leg up on their traditional counterparts.

Bolt Threads is going places, too. It recently teamed up with British designer Stella McCartney to create a couple of garments, including a gold dress for the Museum of Modern Art’s exhibition, Items: Is Fashion Modern?. There’s been the promise of more to come, along with forthcoming collaborations with brands like Patagonia, though details are hush-hush for now.

There might even be another hat drop in the future. Keep your eyes—and heads—peeled.

+ Microsilk Cap of Courage $198

+ Best Made Co.

+ Bolt Threads