I wonder what the class sr-only is? Is it important or can I remove it? Works fine without and no explanation is given in the documentations. Here's my example: <div class="btn-group"> <button type="button" class="btn btn-info btn-md">Departments</button> <button type="button" class="btn btn-info dropdown-toggle btn-md" data-toggle="dropdown"> <span class="caret"></span> <span class="sr-only">Toggle Dropdown</span> </button> <ul class="dropdown-menu" role="menu"> <li><a href="#">Sales</a></li> <li><a href="#">Technical</a></li> <li class="divider"></li> <li><a href="#">Show all</a></li> </ul> </div>