The Mecablitz 15 MS-1 ringflash offers wireless TTL control when used as a slave flash in conjunction with a built-in or on-camera flash. The Metz Synch Cord 15-50 for Mecablitz 15 MS-1 Wireless Digital Ringflash offers the option of 6 user-selectable levels of power output for macro work for those who own cameras without a built-in flash or who prefer manual control for critical work.