**Secondary** - The Secondary is the removable core structure in the upper torso that consists of the PDBMTI, Link, Zelda and various Turbodrivers.
* Mass Sim
**Mass Sim** - The Valkyrie robot platform was designed from the start with battery use in mind. The Mass Sim approximates the weight of a full battery, and offers some capacitance. The capacitance in the Mass Sim protects the robot from back EMF.
