It was developed by the Romulan-Klingon Alliance and was particularly designed to work against androids. The weapon fired a blast of radiation that was capable of incapacitating a positronic brain leaving an android inactive. Repeated shots increased the time the android remained in such a state and it was described that the activity left in the positronic brain was the closest thing that resembled pain to an android mind.
Subcommander Taris of the Romulan Warbird Haakona used a number of hand held weapons to terrorise the android colony of Turing and threatened to use her warships weapon grade anti-positronic disruptor against them if they resisted. (TNG - Myriad Universes novel: Brave New World)