The Electro-Suppressor is a weapon found within the Mothership Zeta DLC in Fallout 3. It is a unique variant of the Shock Baton. It deals more damage. However, while the Shock Baton may cause the enemy to enter a paralysed state for a few seconds, the Electro-Suppressor does not cause any shock damage whatsoever.
It is located in the Engine Room, laying on a table near some Drones.