If you're purchasing a MagicShine 29489 or 30864 Head Lamp or already have one at home this 5.4mm Male to Female Extension Cable will help to simplify installation and give you more flexibility when mounting the bicycle light. The extension cable makes it possible to distance the head lamp from the power source. At 100 centimeters in length the cord is simple to connect with one male end and one female end. Made from high quality water-resistant materials the extension cable is very durable and will last for years to come. The cord weighs slightly more than 1 ounce so it won't add extra weight to your bike.