I also use the batteries for my Mag-Lite 3D-Cell I professionally night use almost daily. I have the batteries now about 2 months into my Mag-Lite and so far they show no weakness. Although I must say that other manufacturers have a long endurance. But I use mostly only brand batteries as Varta or Duracell because I've always had good experiences with those who Mag-Lite remains bright and long the batteries will last very long. With favorable batteries I had ever the problem has eased the luminosity after a few days. I can only recommend the batteries.
