"Corrosion resistant visor with built in respirator provides excellent toxic damage mitigation."
The Medusa Helmet is a helmet made by Atomic. Like the rest of the pieces that make up the Atomic Medusa Series, it is specialized in Chemical/Toxic defense, and is therefore weaker in the physical and thermal departments. This helmet is good for people who:
Wish to have massive Chemical defense to deal with those acid zombies.
This helmet surpasses the Hardplate Helm (without the reload time and movement penalty) and the Dragonfly Helmet in terms of Chemical defense, but falls behind when it comes to Physical and Thermal defense.
In Atomic's Official description, it talks about a helmet that "will let you to dip your head in hydrochloric acid", referring to the Medusa Helmet, and it's high Chemical defense.