Synth relay grenade

The synth relay grenade is a weapon in Fallout 4.

Gameplay
Tossing a synth relay grenade causes a level 5 generation 1 synth to spawn where it lands, and serve as reinforcement.

Locations

 * Allies of the Institute can purchase up to 30 synth relay grenades at a time from the synth requisition officer after the main quest has been completed.
 * Eight grenades are found lying on a table in the small weapons testing area of the Institute Advanced Systems area.
 * Five grenades can be found on a shelf in the Institute Synth Retention Bureau.
 * Three grenades can be obtained via a Speech challenge from the Courser during the Institute version of the quest The Battle of Bunker Hill.
 * Can be found by pickpocketing an Institute Courser's main weapon from their inventory, exiting, then checking again. They'll equip the grenade, and it will become visible for stealing.
 * Can be found as loot on Coursers at higher levels.