Weapon Rack
Prerequisite
-
The mech has numerous holsters, harnesses, and other fittings that can hold spare weapons. As a move action, the mech can store one weapon it’s currently wielding in one or more of its upper limb slots, placing it in the weapon rack. As part of that same action, the mech can also draw one weapon from the weapon rack, automatically installing it for immediate use. The weapon rack can be used only to store weapons that occupy upper limb slots, and the rack can hold a number of weapons with a total number of combined slots no greater than 4.
Source
Tech Revolution pg. 108