The Exposure Diablo Mk4, with a Competitive Cyclist exclusive handlebar and helmet mount, offers 1100 lumens of light, yet it does this while only tipping the scale a hair over 100g -- and itAAAs self-contained. If you've ever snagged a power cord and had your singletrack tunnel go dark or would never consider spoiling a beautiful frame by running cables all over it, then you know the appeal of cable-free lights. The Diablo Mk4's 3100mAh Lithium-ion battery is enclosed within aerospace grade, exquisitely CNC'd aluminum body. That extensive machining, however, isn't just to look cool. It's actually designed to help heat transfer -- to physically cool the light. Packing three Cree XPG R5 LED's, the Diablo Mk4 can generate excessive heat. One way it's managed is through the weather-tight body, the other way it's managed is with Exposure's patented Intelligent Thermal Management (ITM). If the internal temperature gets too high, ITM kicks in and automatically drops the power level down to the next lowest setting. It will remain at the lower setting until the temperature inside the housing returns within normal operating range. This, and the weatherproof housing, ensures the light's battery and LED bulbs are safe from moisture, muck, and heat for a long life span. A defining feature found here on the Diablo Mk4 is Exposure's Smart Port Technology Plus. Essentially, it's a cylindrical plug on the back of the lamp unit that allows you to insert the smart charger. But, it also enables you to plug in accessories like a red LED taillight and back-up batteries, or to even charge other USB-powered devices. It will automatically recognize each accessory and configure the system to take a charge or power accessory lights. Best of all, a remote switch is available for quick light control. A new feature found on the Diablo Mk4 is Exposure's Optimum Mode Selector. OMS offers eight pre-programmed settings to provide the optimal lighting for ride conditions.