function showTab(obj) {
  
  if ( $('pi-tabs-desc-cont') ) {  
    desc_cont = $('pi-tabs-desc-cont');
    desc_cont.style.display = 'none';
    $('pi-tabs-desc').className = 'pi-li-inactive';
  }
  
  if ( $('pi-tabs-perf-cont') ) {
    perf_cont = $('pi-tabs-perf-cont');
    perf_cont.style.display = 'none';
    $('pi-tabs-perf').className = 'pi-li-inactive';
  }
  
  if ( $('pi-tabs-acc-cont') ) { 
    acc_cont = $('pi-tabs-acc-cont');
    acc_cont.style.display = 'none';
    $('pi-tabs-acc').className = 'pi-li-inactive';
  }

  if ( $('pi-tabs-bundled-cont') ) {  
    bundled_cont = $('pi-tabs-bundled-cont');
    bundled_cont.style.display = 'none';
    $('pi-tabs-bundled').className = 'pi-li-inactive';
  }
  
  if ( $('pi-tabs-accessories') ) {  
    bundled_cont = $('pi-tabs-accessories-cont');
    bundled_cont.style.display = 'none';
    $('pi-tabs-accessories').className = 'pi-li-inactive';
  }

  obj.className = 'pi-li-active';
  $(obj.id + '-cont').style.display = 'block';
}