It’s a simple design, but it’s causing quite the ruckus.

Last month, Cheong Choon Ng, founder of Rainbow Loom, maker of popular jewelry kits that go by the same name, filed suit against Zenacon, which also makes similar bracelet kits called FunLoom. Ng says the rival company is infringing his patent because it copied his “distinctive trade dress” of a central part of the product.

The dispute centers on a c-shaped clasp, which allows users to connect colored rubber bands to form bracelets—which have become a popular new product among young girls in the past year. The fasteners are an integral part of the design because they hold together the bands to form the bracelet.

But here’s the catch: Ng didn’t invent looming technology. It’s been around since the 1800s. Regardless, Ng arugues that he’s responsible for creating this new market that relies on the technology.

“I made this famous,” Ng told the Wall Street Journal (WSJ). Ng claims he’s sold more than 1.2 million Rainbow Loom kits since he launched his business three years ago. “I worked on it for three years and now everyone wants to come in.”

Zenacon founder Steven Verona says Ng’s suit is meritless and claims he and his company have done nothing wrong. “Is a loom something new and novel? It isn’t,” he said to the WSJ. “It has been around for hundreds of years. Same as rubber bands,” he says.

Verona argues that even though the two designs are similar, they aren’t the same. He claims his design is superior to Ng’s, offering a larger c-ring and has extra rows for pins.

But at the end of the day, Verona says he would just like the suit to end on a positive note. “We’re hoping to resolve this amicably and have healthy competition in the marketplace,” Verona says. “The better product will be the one that wins.”

Zenacon isn’t the only target of Ng’s patent claims. In August, the Rainbow Loom founder also sued another rival kit maker and Toys R Us, which sells those kits. Ng also entered into an exclusive contract with craft retailer Michael Stores Inc. last month.

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