Why can't I put this in replicated storage?

I'm working on an RPG game, but for some reason when I try to add the armor into replicated storage, its not letting me. Please help me with this. Why can't I add certain objects into the replicated storage?

Try using ServerStorage instead, unless you plan on making it's contents accessible from a LocalScript. If you need to use ReplicatedStorage, enter this in the command bar:

part.Parent = game:GetService("ReplicatedStorage")
--replace 'part' with the path to the object