Borrowed chord common in rock music: I <span class="music-symbol" style="font-family: Arial Unicode MS, Lucida Sans Unicode;">♭</span>VI IV. In C: C A<span class="music-symbol" style="font-family: Arial Unicode MS, Lucida Sans Unicode;">♭</span> F.
<a href="//commons.wikimedia.org/wiki/User:Hyacinth" title="User:Hyacinth">Hyacinth</a>
<span class="int-own-work" lang="en">Own work</span>