Chest unit

The chest unit was a component of the Cyberman body which augmented the chest, containing the ventilator unit. (PROSE: Earthshock) At the front was the chest panel. (TV: Silver Nemesis)

After being shot through the chest aboard a Mondasian colony ship, Bill Potts was fitted with a chest unit prior to her cyber-conversion into a Mondasian Cyberman. commented that it digged in when they hugged, hurting his heart. (TV: World Enough and Time)

A Cyber-Controller which resided on Telos had a chest with no visible panel. (TV: The Tomb of the Cybermen) Later, its body was modified to more closely resemble that of the subordinate Cybermen. (TV: Attack of the Cybermen)

In the 21st century, the Cybermen who attacked Space Station W3 had energy weapons built into their chest units. (TV: The Wheel in Space)

As a target
Lady Peinforte and Richard Maynarde used gold-tipped arrows to kill Cybermen by striking their chest panels. Likewise, Ace used a slingshot to fire gold coins at the Cybermen, with the Seventh Doctor instructing her to aim for their chest panels. The Cyber-Leader was able to survive a hit to its chest panel, removing a coin from its chest unit, only to be killed when Richard thrust a gold arrow into its chest unit. (TV: Silver Nemesis)