/**
  * Prepare columns for products grid
  *
  * @return Mage_Adminhtml_Block_Widget_Grid
  */
 protected function _prepareColumns()
 {
     if ($this->getUseMassaction()) {
         $this->addColumn('in_products', array('header_css_class' => 'a-center', 'type' => 'checkbox', 'name' => 'in_products', 'inline_css' => 'checkbox entities', 'field_name' => 'in_products', 'values' => $this->getSelectedProducts(), 'align' => 'center', 'index' => 'entity_id', 'use_index' => true));
     }
     $this->addColumn('entity_id', array('header' => Mage::helper('catalog')->__('ID'), 'sortable' => true, 'width' => '60px', 'index' => 'entity_id'));
     $this->addColumn('chooser_sku', array('header' => Mage::helper('catalog')->__('SKU'), 'name' => 'chooser_sku', 'width' => '80px', 'index' => 'sku'));
     $this->addColumn('chooser_name', array('header' => Mage::helper('catalog')->__('Product Name'), 'name' => 'chooser_name', 'index' => 'name'));
     return parent::_prepareColumns();
 }