From ROI Wiki

Screamers are a unique defensive technology employed exclusively by Earthfleet, primarily on their shipkillers, which are designed to act as decoys to draw attention away from the mothership similar to the way that chaff and flares act draw away missiles that are attacking a jet in flight. A typical screamer is a spherical device about 3 feet tall that contains numerous devices designed to light up an enemy's sensors so brightly as to either blind them or hide its mothership should they be at risk of being detected, or even if they are, and need to break contact. Screamers are also able to take control of instances of holographic cloaking from the mothership and fly away with them, drawing the enemy away while sacrificing themselves so that their mothership can make good on its escape. Screamers are single use devices, only able to travel at one quarter sublight over short distances, and have no FTL capabilities. Once they have served their purpose, or they run low on power, they self destruct, if they have not already been destroyed by this time, in order to protect the technology inside them from being captured, as they are unlikely to ever be recovered by the ship that deploys them. Most ships, regardless of size, only carry between twenty and thirty screamers in total, as they are only expected to be used occasionally at best. Thus, the likelihood of deploying all thirty on a single operation is considered to be highly unlikely.