Professional Grade Earplugs are earplugs that prevent Plankton from hearing Squidward's clarinet playing in the episode "Sweet and Sour Squid."
The earplugs are a light magenta color, and they fill the user's ear to block out noise.
Role in episode
wears them after having his ears nearly injured because of Squidward
's bad music. He later loses them, which leads to Squidward's clarinet
being destroyed and Plankton's arrest.