The Pulsar is slightly larger than a quarter and weighing 7 grams, provides instant illumination for any situation and offers easy battery replacement. This compact UltraBright LED burns with unbelievable intensity making it the perfect choice for key chains, backpacks, book bags, zippers and emergency situations. Red light helps protect night vision. Specifications: Power: 4 Lumens Lamp: 1 Ultrabright LED Burn Time: 12 Hours Batteries: 2 2016 Lithium Coin Cell Weight: 7g Single Mode: Wide 10m Beam Length