Callisto Pulse

The Callisto Pulse was a device of sorts that could disarm micro-explosives from within up to 20 feet.

It later ended up in the possession of River Song. (DW: The Pandorica Opens)

River Song offered the pulse to Dorium in exchange for a vortex manipulator she required to reach The Doctor. It was required by Dorium to disarm the micro-explosives that he had drunk from his glass of wine. The Pulse was in the form of River's earring. (DW: The Pandorica Opens)

Behind the scenes
According to The Brilliant Book 2012, a non-canonical REF book; it was stolen by the Corsair from the Callistan Klepocracy, on a mission for the Celestial Intervention Agency.