Bootstrap: equal heights in div rows

HTML:

<div class="equal-heights">
 <div class="align-self-stretch">
 </div>
 <div class="align-self-stretch">
 </div>
 <div class="align-self-stretch">
 </div>
</div>

CSS:

.equal-heights {
 display: flex;
}

For more info please check:
https://getbootstrap.com/docs/4.3/utilities/flex/#align-self