<div class="btn-group">
  <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
    Action <span class="caret"></span>
  </button>
  <ul class="dropdown-menu" role="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>

<div class="btn-group">
  <button type="button" class="btn btn-primary">Action</button>
  <button type="button" class="btn btn-primary dropdown-toggle" data-toggle="dropdown">
    <span class="caret"></span>
    <span class="sr-only">Toggle Dropdown</span>
  </button>
  <ul class="dropdown-menu" role="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>

<div class="btn-group">
  <button class="btn btn-primary btn-lg dropdown-toggle" type="button" data-toggle="dropdown">
    Large button <span class="caret"></span>
  </button>
  <ul class="dropdown-menu" role="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>

<br><br>

<div class="btn-group">
  <button class="btn btn-primary btn-sm dropdown-toggle" type="button" data-toggle="dropdown">
    Small button <span class="caret"></span>
  </button>
  <ul class="dropdown-menu" role="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>

<br><br>

<div class="btn-group">
  <button class="btn btn-primary btn-xs dropdown-toggle" type="button" data-toggle="dropdown">
    Extra small button <span class="caret"></span>
  </button>
  <ul class="dropdown-menu" role="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>