... 2.convenient,smart,portable,practical 3.an alarm or signal in dark. 4.Perfect design. 5.fast shipping wireless brake light/lampapplication ... bike,bike,hand etc.When you brake the bike/car in dark, will sense the lamp twinkle, give an alarm or signal ... light/lamp2.convenient,smart,portable,practical3.an alarm or signal in dark.4.Perfect design.5.fast shipping wireless brake light