Edwards 93 Xenon strobe beacons are heavy duty visual signals suitable for use where more frequent and longer lasting signaling cycles may be required. Optically designed fresnel lenses improve viewer perception for indoor and outdoor applications. The 93DF and 97DF Series offers a double flash model that doubles the apparent strobe on-time (50 double flashes per minute). Trigger and timing circuits are included as integral parts of the power supply. Replacements costs are reduced, as it is necessary to replace only the strobe tube.