OVERVIEW: 
The AN/SLQ-49 Chaff Buoy Decoy System, commonly referred to as "Rubber Duck", consists of inflatable radar-reflecting decoy buoys. Used by the U.S. Navy, Royal Navy, and other NATO countries, the decoy is designed to seduce radar-guided anti-ship missiles by simulating the radar cross section of a ship. When deployed, the system launches into the water two octahedron-shaped inflatable decoy floats, connected by a 5-metre (16 ft) cable.

The AN/SLQ-49 has been in operation since 1985. Originally designed to confuse or distract enemy radar operators, it has demonstrated effective missile seduction capabilities.

SOURCE:
Wikipedia http://en.wikipedia.org