Fresh-faced pop stars like Harry Styles and Taylor Swift have no shortage of gushing fans to trip over themselves for concert tickets and autographs. But it is metal—yes, metal, meaning decades-old groups like Black Sabbath, Iron Maiden, and Kiss—that actually has the most loyal fans, it turns out.

That’s per Spotify data analyzing the genres with the highest global loyalty, measured by the number of streams divided by the number of listeners per artist. Metal is number one by far on the list, ahead of genres like hip-hop, country, and rock by as much as 50%. In the US alone, metal has about twice as much listener loyalty as EDM, rap, or jazz.

Billboard reports that a new online streaming service, Gimme Radio, now offers a “radio service and collectible marketplace” exclusively for metal. It aims to fill in a gap between interest and supply, since most metal bands up till now have preferred to stick to CDs and vinyl records instead of moving on—as more fast-paced and youthful genres like hip-hop already have—to promoting their music primarily on streaming platforms. “We’re not chasing dozens of millions of subscribers or aiming to feed music down a pipe to as many people as possible,” Gimme CEO Tyler Lenane told Billboard. What he sees the company doing is offering metal fans an avenue for “more engagement than just a digital stream.”

That’s smart strategy. In the age of buffet-style streaming services, genuinely devoted fans are looking for ways to more deeply connect with favorite artists, whether attending hyper-specific music festivals or trying to use Spotify and Apple Music as personalized sources of curation, rather than utilitarian tools. The market for streaming is oversaturated—yet the market for products for true music lovers is underserved.

Why does metal has such loyal fans? It likely comes down to a combination of niche attraction, the intensity of the music itself and the types of relationships that listeners tend to form with it—and metal’s aging community of fans, who have now hit the prime point of exquisite cultural nostalgia.