The ForceField Torso is a torso part exclusive to Rimtech. It's primary function is protection against high-damage, slow-rate-of-fire ranged attacks. The first attack that strikes the combot is intercepted and neutralized by an energy field, presumably using the same technology as the Point Defense Array. However, the shield can only protect from one attack and once used, it takes a couple of seconds to recharge and redeploy.
The shield operates passively and - aside from the recharge time - is always active.
it requires a Research Facility to be produced.
Official Description[]
"When activated, the Force Field Torso will create a visible protective shield around the wearer. This force field is designed to absorb a single Incoming projectile, missile or shell. After it is struck, the force field must initiate an automatic recharging procedure for it to be effective again. At this point, the Torso functions like a Basic Torso, Ieaving the Combot vulnerable to attack."