F11 is a dominant eleventh chord made of 6 notes: F, A, C, E♭, G, B♭. It sounds thick and open, and you hear it in soul, funk and fusion, often played without the third. It is the V chord of B♭ major and turns up in 2 other keys.
The library above opens on F11 with 14 shapes up and down the neck. Tap a shape to hear it, or play it one string at a time.