Diver down flag. A diver down flag, or scuba flag, is a flag used on the water to indicate that there is a diver below. Two styles of flag are in use. Internationally, the code flag alfa/alpha, which is white and blue, is used to signal that the vessel has a diver down and other vessels should keep well clear at slow speed.
Familiarize yourself with some friendly network cables and take a closer look at common types of network media, including twisted-pair cable, coaxial cable, fiber-optic cable, and wireless.
There are three types of fiber optic cable commonly used: single mode, multimode and plastic optical fiber (POF). Transparent glass or plastic fibers which allow light to be guided from one end to the other with minimal loss. Fiber optic cable functions as a light guide, guiding the light introduced at one end of the cable through to the other end. The light source can either be a light-emitting diode (LED)) or a laser.