Slightly larger than a quarter and weighing only 7 grams, the Princeton Tec Pulsar Light provides instant illumination for any situation, and offers easy battery replacement. This compact, ultra bright LED burns with unbelievable intensity making it the perfect choice for key chains, backpacks, book bags, zippers and emergency situations. Super bright white LED light. Squeeze the center and the Pulsar provides reliable light for any situation. Hook it to your backpack, book bag, or keychain for instant light. Burn time of 12 14 hours. Weight 7 grams with batteries. Two Lithium coin cell batteries included.