sidebar-customer.php

<div class="row ">

  <div class="col-lg-12">
    <h2 class="page-header">Our Customers</h2>
  </div>

  <div class="list_carousel">
    <div id="foo2">
      <div class="col-md-2 col-sm-4 col-xs-6">
        <img class="img-responsive img-customer" src="<?php echo get_stylesheet_directory_uri(); ?>/assets/img/clients/forbes.png">
      </div>

      <div class="col-md-2 col-sm-4 col-xs-6">
        <img class="img-responsive img-customer" src="<?php echo get_stylesheet_directory_uri(); ?>/assets/img/clients/guardian.png">
      </div>

      <div class="col-md-2 col-sm-4 col-xs-6">
        <img class="img-responsive img-customer" src="<?php echo get_stylesheet_directory_uri(); ?>/assets/img/clients/mashable.png">
      </div>

      <div class="col-md-2 col-sm-4 col-xs-6">
        <img class="img-responsive img-customer" src="<?php echo get_stylesheet_directory_uri(); ?>/assets/img/clients/ny-times.png">
      </div>

      <div class="col-md-2 col-sm-4 col-xs-6">
        <img class="img-responsive img-customer" src="<?php echo get_stylesheet_directory_uri(); ?>/assets/img/clients/red-bull.png">
      </div>

      <div class="col-md-2 col-sm-4 col-xs-6">
        <img class="img-responsive img-customer" src="<?php echo get_stylesheet_directory_uri(); ?>/assets/img/clients/natural_grey.png">
      </div>
    </div>
  </div>

</div>