Features household-style sync terminal (automatically overrides slave), 1/4"-20 threaded socket, for tripod/light stand mounting and hardware necessary to make Vivitar repairs. * No hard-wiring necessary, installation requires only a #0 screwdriver. Simply slide them onto flash hot shoes, and that"s it. Or, attach PC cord (not supplied) from flash to slave"s PC terminal. * "Surround Sync" design ensures omnidirectional performance. Slaves are cast in plastic for incredible durability and integrated with a precision, extruded aluminum housing for "bulletproof" design.