With an array of new products and exclusive items, Disney (DIS) is not simply rewarding passionate fans. It is also recognizing the role collectors play in stoking excitement around one of its most important franchises.

“Star Wars” items were the U.S. toy industry’s top-selling line for 2015 and 2016 with $1.5 billion in sales over the two years, research firm NPD said.

Disney, the world’s largest entertainment company, bought “Star Wars” producer Lucasfilm in 2012 and began developing new movies in the celebrated science fiction franchise. The company then expanded the range of related products to attract both casual and serious collectors, working with licensees on everything from $8 bobbleheads to a $7,000 life-size Darth Vader figure.

“The volume of it has been unprecedented,” said Gus Lopez, a well-known “Star Wars” collector who has co-authored five books on the subject. “It’s on a new level.”

Collectors are a key part of Disney’s “Star Wars” business, says Jim Silver, editor-in-chief of toy review site TTPM.

NPD reported that about 3% of “Star Wars” sales in 2016 came from collectibles, defined as certain types of trading cards, action figures, and other products for collectors.

Silver estimates that the share of sales to collectors is much higher, as much as 33% to 45%, based on industry data about purchase habits, the age of buyers and the types of products bought, such as the more-expensive action figures.

After acquiring Lucasfilm, Disney and its licensees created a range of new collectibles, including Elite Series action figures, which are die cast and heavier than plastic ones, Silver said. The figures flew off Disney Store shelves when they were released around the December 2015 debut of the movie “The Force Awakens,” Silver said. “They couldn’t keep them in stock,” he said.

Products come in a variety of price ranges. Bobbleheads from toymaker Funko, selling for $8 to $20, have become a hit.

“Some fans buy every figure made and various poses of the same character,” said Paul Southern, senior vice president of Star Wars licensing at Disney’s consumer products and interactive division.

For well-heeled collectors, Disney licensees offer limited-edition high-end items billed as works of art and promising to replicate what is seen on screen. Companies such as Sideshow and Hot Toys offer statues, for example, that Southern said “capture every detail down to Rey’s last freckle.”

Collectors “are willing to invest in ultra-detailed items,” he said.

Offering exclusive merchandise at events like Star Wars Celebration and San Diego Comic-Con, as well as at Disney theme parks and in Disney Stores and other retailers, helps stir fan fervor.

At the current Star Wars Celebration, limited edition items include Hasbro Inc’s Luke Skywalker figure in X-Wing pilot gear and two assassin droids from Japanese company Kotobukiya. Funko is selling new bobbleheads including a Princess Leia figure, which also were made available through retailer Box Lunch.

Quantities are not always disclosed, but collectors said the items are usually produced in batches of hundreds or thousands.

Attendees may spend hours in line to score the hottest items, according to collector Jake Stevens, who said he once waited four hours to buy a Darth Vader action figure that uttered lines recorded by actor James Earl Jones. This year, some manufacturers have created online lotteries for spots to buy products.

“The collectibility of show exclusives has definitely gone through the roof,” Stevens said.

Adding to the appeal, many of the newest products sport a 40th anniversary logo to mark the four decades since the 1977 debut of the original “Star Wars” film.

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Disney will release the eighth episode in the film saga, “The Last Jedi,” in December.

Industry experts say that collectors help spread a type of enthusiasm for franchises that companies cannot generate through traditional advertising or marketing.

Collectors are active on social media, in website forums and on podcasts. They share details about their latest finds and where to pursue new merchandise. A day before the start of Star Wars Celebration, enthusiasts were already circulating photos of Hasbro boxes arriving at the venue.

“A huge percentage of those collectors are the franchise’s biggest fans, advocates and social media influencers,” said Marty Brochstein, a senior vice president at the International Licensing Industry Merchandisers’ Association. “They’re the kind of fans who help create buzz at the core, which radiates out to the population at large.”