This light is Big Blue's version of a marker light. Low light output so it is not distracting but bright enough to be seen by other divers. This light easily clips on to mask straps, belts, straps and any many other locations. Each light can be set to illuminate in one of three color choices: Red, Blue and Green. A Rainbow version is available with red, green, blue, purple, orange, and yellow in single unit and a flash mode as well. Powered by 2x standard CR2032 coin cell batteries, the Easy Clip can last up to 72 hours without changing batteries. A Lanyard is included to keep it attached to your equipment.