Synth relay grenade

The Synth relay grenade is a weapon in Fallout 4.

Characteristics
Toss a synth relay grenade to spawn synth reinforcements at a target location.

Locations
Obtained via a speech challenge during The Institute Quest: The Battle of Bunker Hill.

Allies of the Institute can also purchase synth relay grenades from the Institute requisitions vendor after all Main Quests are completed.