SHIELD Missile Defence System

When potential enemies developed guided missiles as a threat to warships, this device was developed to fire rockets which burst and release a cloud-like mass of metal foil or other radar-deflecting material called “chaff.” Chaff is made of metal or of non-conducting fibres coated with a conducting material. Aluminum foil use is quite common, as are glass and nylon fibres coated with aluminum or zinc. This confused the enemy’s rocket guidance radar and diverts the missiles from its intended target. 

The payload is a stack of circular cassettes of aluminized or fibreglass strands of varying lengths, dispersed by gas charge. 

Other types can emit bursts of light/heat to divert heat-seeking or infrared missiles.

Reference Links:
Youtube - Chaff (countermeasure)