I have two light engines, one older (100L?) and one of the 200L models and I hate the battery holders on these things. The 9V connector is problematic at best since it tends to uncouple at the worst times, like on a bumpy section of trail. I have broken a number of the battery holders - luckily they are cheap to replace. It looks like the newer 400L units are more robust but in the 200L range I have switched over to using a P7 flashlight setup - 900L for under $50.00.