The Sea & Sea YS YS-01 is a slave strobe flash that operates underwater. This strobe flash is compact and works with both DSLR and point-and-shoot cameras. With multiple exposure options, the Sea & Sea YS YS-01 Underwater Strobe Flash is optimal for wide-angle and macro photography. The device has a circular beam angle of 100 x 100 degrees and a guide number of up to 20. With the DS-TTL feature, the Sea & Sea YS YS-01 allows the user automatic exposure control in slave mode. The device's ten-level power dial allows the user to easily move from one mode to another for greater shooting versatility. The Sea & Sea YS YS-01 Underwater Strobe Flash is designed to operate well in the specific lighting conditions of coral reefs and other underwater settings. The fast 1.9 second recycle time ensures a fast turnaround for pictures and the device has a bright 1W LED target light for use on night dives. The Sea & Sea YS YS-01 Underwater Strobe Flash's color corrected strobe light also brings back the natural colors that fade as the photographer descends deeper. In addition, a Strobe Mask Set attachment ensures the on-camera flash does not over-expose the subject. The YS-01 is well equipped to operate in the challenging settings of underwater environments.