A neutralization emitter was a Cardassian device which surrounded its target with an energy field for restraining purposes. It could cause death to the person surrounded after an unspecified duration of contact.
Terok Nor, later called Deep Space 9, was equipped with these emitters. After the Cardassian withdrawal from the station in 2369, they were disabled by Starfleet and Bajoran personnel but left in place. When a counter-insurgency program was inadvertently activated in 2371, the neutralization emitters were used to short out all force field emitters on the station to permit evacuation. (DS9: "Civil Defense")