Slightly larger than a quarter and weighing only 7 grams, the Princeton Tec Pulsar II Light provides instant illumination for any situation, and offers easy battery replacement. And, with a flick of a switch, the Pulsar II stays on so you can free up your hands for other tasks. This compact, ultra bright LED burns with unbelievable intensity making it the perfect choice for key chains, backpacks, book bags, zippers and emergency situations. Constant on off switch for continuous illumination. Super bright white LED light. Squeeze the center and the Pulsar II 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.