White Castle continues its partnership with fashion designer Telfar Clemens by offering specially-designed holiday mugs. The celebrity partnership is just one of many by White Castle as the legacy quick-service chain maintains relevance in a competitive market.

Each year, White Castle releases a special holiday mug for collectors. Telfar Clemens, the founder of the TELFAR fashion line, designed the limited-edition mugs. Consumers can pick them up for $5.99 and the net proceeds will benefit Robert F. Kennedy Human Rights bail fund for school-age youth on Rikers Island.

Clemens first partnered with White Castle last year when he created designer uniforms for the chain’s stores. He and his creative partner, Babak Radboy, were inducted into the White Castle’s ‘Cravers Hall of Fame’ soon after. Clemens is designing the third line of employee uniforms that will be released in 2019.

Founded in 1921, the White Castle brand is still privately-owned. While this allows complete control over how the restaurant is presented to consumers, it also means that you won’t see a White Castle restaurant on every street corner. It may be credited as the first fast food burger chain, but it was far from the last—so remaining in the public conscious remains a challenge White Castle’s CMO, Kim Bartley.

“We’ve been able to weather a lot of changes in the economy and how people eat simply because we’re flexible,” Bartley told Brand Channel in a 2017 interview. “We just have to figure out a way to continually keep our brand top of mind.”

Bartley led a company-wide rebrand effort last year with “Bold Move.” Appealing to young consumers’ desire for individuality, the campaign encourages them to try White Castle for the first time or in a new way.

One such method was appealing to the health and animal-conscious consumer. White Castle added meat-free Impossible Burgers to the menu and a vegan bun. Promoting the new menu item included a video series called “Wu-Tang in Space.” RZA, GZA, and Ghostface Killah star in four episodes as they bestow knowledge upon Earthlings everywhere.