A flexible keyboard that unrolls flat like a mat, played by Lieutenant Commander Nella Daren aboard the Enterprise-D and used in her duets with Picard's Ressikan flute in Lessons.
Nella Daren, who takes charge of stellar sciences on the Enterprise-D in 2369, is an accomplished pianist. Her instrument, seen in the sixth-season episode Lessons, is a thin flexible strip with a printed keyboard that can be rolled up, carried under an arm and laid out on any flat surface.
She performs at a recital in Ten Forward with Data, and then persuades the captain, who has kept his playing private since the events of The Inner Light, to bring out his flute. The two play together in his quarters and later in a Jefferies tube junction that she has identified as the most resonant spot on the ship.
The duets, including the melody Picard learned on Kataan, carry the romance between them. It ends after he has to send her into danger on Bersallis III and both conclude they cannot serve together.