Surprisingly bad - SureFire M640DF Scout Light Pro Dual Fuel LED Weapon Light

This light is unreliable! After only a few months and some range time it began to degrade in light output with a freshly charged battery. This problem only grew with flickering, failure to illuminate, and flat out not illuminating with the tail cap depressed. Given the features and output there are several other manufacturers with better options at this price point. I would say skip Surefire and their abysmal customer service. I would highly suggest searching problems with surefire df models, the web is full of YouTube videos, forum discussions, and truthful reviews of this sub par product.