See.Sense. 2.0 INTENSE Rear Light - 125 Lumens Intelligent Sensor Technology - See.Sense continually monitors motion, orientation and light. Both the front and rear lights use this technology to monitor the bicycle and its environment. It responds to road conditions  junctions, roundabouts, filtering in traffic, approaching headlights and more. So its the first bicycle light than can respond to your situation, flashing brighter and faster, to make you more visible when you most need it most. Long Runtime - See.Senses efficient power usuage means it can be bright but with around 12 hours run-time, depending on usage. Variations are due to the light changing its flash patterns at times of increased risk. We expect a commuter using this light to easily obtain 12 hours. The lithium ion battery recharges from any USB socket. The See.Sense Fuel Gauge lets you know the remaining runtime. Your See.Sense will never run out of charge unexpectedly. Wide Visibility - Most cycle lights have a narrow beam which is only effective when a car is approaching from behind. We think what you really need is side visibility and so weve deliberately used Fresnel lens elements to increase the viewing angle of our light, helping you be seen from every angle. It even illuminates you and the road around you. This helps drivers high up in HGV cabs and motorists viewing you from a side angle see you much better. This extra wide viewing angle also means our lights can be really bright, without dazzling drivers. Our progressive optics spread the light more than 180 degrees, giving you effective side visibility. Small, Compact & Sturdy - Small and compact at 5.8 x 3.8 x 4.8 cm (2.3 x 1.5 x 1.9 inches), and very light at around 55 grams. The lens is made from Lexan (the same tough polycarbonate used in the helmet visor in the Apollo moon missions!). The casing is made from Luran S, a very tough ASA plastic. Weve used the finest materials for the finest bike light.