function addToCart(id, strProductName, strProductSku, strProductUnits) {
  showOverlay();
  // update form
  $('product_browse_form').getElement('input[name=product_name]').setProperty('value',strProductName);
  $('product_browse_form').getElement('input[name=product_sku]').setProperty('value',strProductSku);
  $('product_browse_form').getElement('input[name=product_units]').setProperty('value',strProductUnits);
  $('product_browse_form').getElement('input[name=quantity]').setProperty('value',$('quantity_'+id).getProperty('value'));

  // clear quantity box
  $('quantity_'+id).setProperty('value','');

  // post form & show cart
  $$('.product_browse_form').send({update: $('ps-cart_iframe').contentWindow.document.body, onComplete: function(){
  	iframeLoadPage('shop/cart');
  }});
}