Redstone Signal Inverter Upgrade
The Redstone Signal Inverter Upgrade is a simple upgrade that, you guessed it, inverts the Redstone signal of a machine. It can be placed inside any machine which can be controlled using a redstone signal, including the Induction Furnace, Thermal Centrifuge, and Advanced Miner. This can be useful when trying to make compact setups, where placing a lever or redstone torch will be unfavourable. It can also be helpful with redstone circuitry, and you want the invert the output before it enters the machine without making an inverter.
See: Crafting Guide