public function setStocklevel( $stocklevel )
	{
		if ( $stocklevel === $this->getStocklevel() ) { return; }

		if ( $stocklevel !== null ) {
			$stocklevel = (int) $stocklevel;
		}

		$this->_values['stocklevel'] = $stocklevel;
		$this->setModified();
	}