<!-- required js / css -->
<link href="/assets/plugins/select-picker/dist/picker.min.css" rel="stylesheet">
<script src="/assets/plugins/select-picker/dist/picker.min.js"></script>

<!-- default -->
<select class="form-control" id="ex-basic">
  <option>Mustard</option>
  <option>Ketchup</option>
  <option>Relish</option>
</select>

<!-- multiple -->
<select class="form-control" multiple>
  <optgroup label="Picnic">
    <option>Mustard</option>
    <option>Ketchup</option>
    <option>Relish</option>
  </optgroup>
  <optgroup label="Camping">
    <option>Tent</option>
    <option>Flashlight</option>
    <option>Toilet Paper</option>
  </optgroup>
</select>