The Egg Pistons Mk. II are the eleventh mini-boss in Sonic Mania, encountered at the end of Metallic Madness Zone Act 1. They are an improved version of the boss of Sonic the Hedgehog's Final Zone, now equipped with five crushing pistons rather than the original's four.
The machine consists of five pistons and a lightbulb-like generator to the right of the screen. Dr. Eggman attacks by trying to crush the player with a random pair of pistons; Eggman himself will be in one of the pistons, and the machine will take damage if the player hits the doctor. In between each pair of pistons firing, the generator produces four electric orbs which descend slowing while homing in on the player's position - as in the original, touching these will damage the player.
Dealing four hits will cause the machine to partially explode and destroy the generator, causing the screen to flash red; once this happens, the pistons begin to fire individually in quick succession. The order in which they fire is random, with Eggman - still the boss's weak point - now standing in every fourth piston. Landing another four hits destroys the machine completely and ends the fight, allowing the player to proceed to the signpost and finish the Act.