B♭5 (also written A♯5) is a power chord chord made of 2 notes: B♭, F. It sounds strong and neutral, with no third to make it major or minor, and you hear it in rock, punk and metal, especially with distortion. It is the I chord of B♭ major and turns up in 5 other keys.
The library above opens on B♭5 with 14 shapes up and down the neck, starting with hand-checked ones. Tap a shape to hear it, or play it one string at a time.