Over the years, Disney theme parks have offered over 200 different varieties of Mickey Mouse ears for guests to wear.
The latest version, which debuted Friday with the relaunch of Disney California Adventure, includes technology that let the ears glow and change colors in sync with the music of shows at Disney theme parks.
But they are not cheap: The price for the glowing ears is $25 while the plain black version sells for about $14 at the park.
The video above shows how the ears glow to the "World of Color" attraction at California Adventure.
Disney officials say the ears include circuitry to receive signals to light up and change colors not only for the "World of Color" show and but also the new "Mad T Party" dance party, inspired by the Alice in Wonderland story.
Merchandise sales typically generate about 20% of theme park revenue, but that percentage spikes when a park offers new souvenirs, clothes and hats that are tied to the opening of a new attraction or holiday celebration, according to theme park industry experts.