This is a Dynalite Sync Cord. One end is a 1/4" "Phono" style plug that fits into any compatible power pack or monolight, the other a PC (Post Connector) plug that fits into your camera. It enables firing of your flash from your camera from up to 16' (5 m) away.
One Year Manufacturer's Warranty
Dynalite Sync Cord, 1/4" Diamater Phono to PC - 16' (5m)