kero/snippets/examples/dt/datatable/combobox/combobox-default/widget.html

<div class="u-combo" id="combo1" style="margin: 10px">
    <div class="u-input-group u-has-feedback">
        <div class="u-input-group-before" style="color: red;">*</div>
       <input class="u-form-control"/>
       <span class="u-form-control-feedback uf uf-anglearrowdown" data-role="combo-button"></span>
    </div>
</div>

<br>
<br>
<div class="u-combo" id="combo2">
    <input class="u-input"/>
    <label class="u-label"></label>
    <span class="u-combo-icon"></span>
</div>