Right out the gate I had an issue with this flashlight. I opened the box and took it out and was about to n put the batteries in. So I unscrewed the battery compartment and left a spring fell out. I didn't know exactly where it went. And after several attempts, I had put it over the existing spring (yes, there was another spring still attached which added to the confusion!) and it finally worked. Super duper bright! And the strobe mode will definitely disorient someone.