<div class="btn-toolbar" role="toolbar">
    <div class="btn-group btn-group-lg">
        <button type="button" class="btn btn-default">Left</button>
        <button type="button" class="btn btn-default">Middle</button>
        <button type="button" class="btn btn-default">Right</button>
    </div>
</div>
<div class="row">
    <div class="col-md-12">
        <div class="btn-toolbar" role="toolbar">
            <div class="btn-group">
                <button type="button" class="btn btn-default">Left</button>
                <button type="button" class="btn btn-default">Middle</button>
                <button type="button" class="btn btn-default">Right</button>
            </div>
        </div>
    </div>
</div>
<div class="row">
    <div class="col-md-12">
        <div class="btn-toolbar" role="toolbar">
            <div class="btn-group btn-group-sm">
                <button type="button" class="btn btn-default">Left</button>
                <button type="button" class="btn btn-default">Middle</button>
                <button type="button" class="btn btn-default">Right</button>
            </div>
        </div>
    </div>
</div>
<div class="row">
    <div class="col-md-12">
        <div class="btn-toolbar" role="toolbar">
            <div class="btn-group btn-group-xs">
                <button type="button" class="btn btn-default">Left</button>
                <button type="button" class="btn btn-default">Middle</button>
                <button type="button" class="btn btn-default">Right</button>
            </div>
        </div>
    </div>
</div>