Building on the button group styles and markup, we can easily create a split button. Split buttons feature a standard action on the left and a dropdown toggle on the right with contextual links.
<div class="btn-group ">
<button class="btn btn-default">Dropdown</button>
<button class="btn btn-default dropdown-toggle" data-toggle="dropdown"><i class="fa fa-caret-down"></i></button>
<ul class="dropdown-menu">
<li><a href="#">Action</a></li>
<li><a href="#">Another action</a></li>
<li><a href="#">Something else here</a></li>
<li class="divider"></li>
<li><a href="#">Separated link</a></li>
</ul>
</div>