Empfehlenswerter battery-double

I had taken the battery double pack on my trip to southern climes. I used within 2 days every three batteries in my Panasonic DMC-TZ41: The original and both cycling extended batteries. A perceived difference so far I could not identify. Whether the batteries are good in the long run, will probably show only after months. First, however, I speak of a recommendation, especially wg. the very good price / performance ratio.