Magicshine rear light of 100 lumens. The lamp has a built-in accelerometer which can detect when you brake hard. When you do, the headlight will flash quickly at full brightness to warn cyclists and motorists behind you. The light sensor selects the correct light setting and adjusts the light to the surroundings. The lamp has several different light settings and can be lit constantly with either 18, 36 or 72 lumens. In addition, there are a number of flashing functions. The lamp can be mounted on both round seatposts and aero seatposts with the included bracket. In addition, it can be mounted on the saddle hangers with other brackets that are also included. The lamp is IPX6 certified.