4 slots next to Electro Furnace

    • Official Post

    These slots are for upgrades,
    Transformer upgrade : increases voltage accepted by machine by one tier. (2 makes it accept HV)
    Overclocker upgrade : increases machine speed, at the cost of more energy.
    Battery storage upgrade : increases internal storage by 10k.
    all upgrades are stackable up to 64

    for recipes check industrial wiki.