SecUnits

"The practice is disgusting, it's horrible, it's slavery. This is no more of a machine than Gurathin is-" ''Exasperated, Overse said, "And you don't think it knows that?" (All Systems Red)''

Security Units, or SecUnits for short, are bot-human constructs intended to provide security for humans and augmented humans, usually through contracts from an equipment supplier.

SecUnits are physiologically similar to humans, and Murderbot is even able to pass as an augmented human with slight alterations (both physical and code-related).

SecUnits have short hair and "generic human" faces. Visible bot material (such as on the head and neck) resembles that of typical augments. However, SecUnits are not designed to act or function like humans, and do not have a variety of human traits and organs.

SecUnits do not need to consume or eliminate matter. SecUnits therefore do not have a digestive system of any kind. Murderbot explains that any food or liquid consumed will end up in its lungs, which it will later need to get rid of (presumably by coughing), and it is incredibly unpleasant for them to do so.

SecUnit lungs are connected differently than human lungs, and are designed to take in much less air. Because of this, SecUnits are unable to perform rescue breathing (Network Effect, p98). SecUnits are able to survive for extended periods of time in a minimal or depleted atmosphere (ex in shipping containers).

SecUnits have metal framework and synthetic bones as the main supporting structure of their bodies. This is presumably very difficult to destroy, as shown by multiple near-fatal injuries to Murderbot leaving it with large pieces of missing flesh but intact bones.

If a SecUnit is damaged, it can go into a repair cubicle to regenerate missing tissue. SecUnits can regrow 80% of their body mass in a repair cubicle, but this does not include the organic parts of their heads.

SecUnits have energy weapons in a compartment on each forearm that can be used to incapacitate humans or to melt through things. These are somewhat effective on each other and can be fatal (ASR, p72), but smaller energy weapons do little to affect SecUnits.

Also, SecUnits don't have any organic matter on their feet.

It's unclear which components of a SecUnit are organic vs inorganic. There isn't ever much explanation about what they look like.