The Mark-Lite LED Strobe is double O-ring sealed, depth rated to { 1000 ft | 300 m }, and provides 11+ hours on one 3.6v size AA lithium battery(Included). Features durable military tough ABS and LEXAN construction, twist on switch with non-slip grip, { 5.75 in | 15 cm } long safety orange color body and clear lens with sturdy attachment point for snap or lanyard. Bulb life is estimated to be 10,000 hours with the Flash rate of 2hz (2 times per second). A 3.6v size AA lithium battery and a bungee strap are included, along with a limited LIFETIME Warranty from TekTite.