Show only first char In select option

HTML

<select id="selectbox1" style="width:1em">    
    <option value="S" class='hide' data-value=''>S</option>
    <option value="S">Second</option>
    <option value="M">Minute</option>
    <option value="H">Hour</option>
    <option value="D">Day</option>
    <option value="W">Week</option>
    <option value="T">monTh</option>
    <option value="Y">Year</option>
</select>

CSS

.hide {
   display: none;    
}

JavaScript

$('#selectbox1').on('change', function(){										    
    var option = $(this).find('option:selected');
    $('.hide').text(option.val()).val(option.val());    
    $('.hide').data('value', option.text());
    $('.hide').attr('selected', true);    
});