Hydraulic Cylinder is a treasure item in Final Fantasy XV needed to complete the A Better Gravity Well quest given by Cid at Hammerhead Outpost.
Final Fantasy XV Hydraulic Cylinder Locations
As of right now, the only known location of a Hydraulic Cylinder is inside the Zegnautus Keep dungeon. As players progress through the dungeon, they will come up on a conference room with screens displaying different flags and a 3D projector in the middle. After killing the enemies in the area, players can move to the central conference table where they will find the Hydraulic Cylinder.
Since so far there seems to be only one location for the item, it is highly advised to not sell this as they will need it to complete the A Better Gravity Well quest. Even if players don’t use the weapon, it is a good way to earn some quick EXP.
After getting the Hydraulic Cylinder in Final Fantasy XV, players need to return to Cid and hand him both the Hydraulic Cylinder and their Gravity Well, which needs to be unequipped first if they are using it as a weapon. Cid will upgrade it into Gravity Well II, although the upgrade process takes some time so players can go out again and do some other side quests while Cid is tinkering with the weapon.