Now that's a small fine idea. A two-piece bicycle light that is held together by magnets. To use the lamps are easily separated from each other and keep up with magnetic force to the bike racks (if they are magnetic, so not with aluminum rims). The lamps are automatically activated. There mehere modes (blinking / permanent light). Contrary to the negative reviews, the lamps are never dropped me and always remained in place in spite of cobblestones and curbs. They have also turned on and off reliably. Since the lamps each have a small LED they are not particularly bright, but still better than no lighting.