For the very best in water-activated personal distress lights, ACR Electronics H2O PFD Lights combine far-reaching LED illumination with increased operating life. Both styles, the C-Lightand C-Strobe, are USCG/SOLAS-approved, 100% waterproof and theyre perfect for after-dark on-the-water emergency situations. The slim, lightweight and versatile design boasts an impact-resistant case that secures to your life jacket, backpack or belt with its Velcro strap, lashing loop or PFD clip. The light can be activated with the on/off button, or use the armed position, and it will automatically turn on if immersed in water. Requires two AA batteries (not included). 5.56L x 1.38W x 1.2D. Wt: 1.4 oz. Available: C-Light H2O LED Steady-on 20-lumen white LED runs for an impressive 30 hours at 86F (30C) or 20 hours at 30.2F (-1C). C-Strobe H2O LED Multifunction light features Strobe/Steady-On/SOS modes. Brilliant 40-lumen white LED runs for up to 120 hours on Strobe mode at 86F (30C). 100 hours at 30.2F (-1C). Cancer and Reproductive Harm- www.P65Warnings.ca.gov. Type: Safety.