public function equals(HWDevice $dev)
    {
        if ($dev->getName() === $this->_name
           && $dev->getCapacity() === $this->_capacity
           && $dev->getManufacturer() === $this->_manufacturer
           && $dev->getProduct() === $this->_product
           && $dev->getSerial() === $this->_serial) {
            return true;
        } else {
            return false;
        }
    }