Tesla power pack

Named Tesla Armor in the game, it is actually a third piece of armor that you can wear on top of any other gear you have. It does not look like the standard glowing tubes on a Tesla suit's back, but does cover them up if you wear it with the main Tesla Armor suit. It will also give you invisible Tesla coils in the same locations as if you were wearing standard Tesla Armor and arcing electricity on anything you wear it with. Wearing the pack will also give you floating tubes that go from the top of the pack to your character's chest. Depending on your outfit, the tubes will appear to terminate just below your collarbones and be floating unsupported.

This can be equipped with any other piece of body armor to add extra Damage Resistance. However if worn with another piece of body armor then 40 Damage Resistance is halved to 20; still an excellent piece of equipment.

This armor also never seems to degrade.

Bug/glitch?
It is believed by many in the community that this item is bugged. It has the same name as normal Tesla Armor and the same stats as Enclave Power Armor. When considered logicaly, a backpack which weighs the same as a full suit of armour is quite ridiculous. Some believe it's not supposed to exist at all and was intended as an npc item only, given the confusing name, strange repair options, and the fact that according to the lists, it shouldn't be dropped or even owned by NPC's. It's possibly something the developers forgot to disable or remove.