3.3 Non-obvious

For a patent application allowed, it cannot be "obvious" even it is novel. 

Sometimes an alleged invention might be new but obvious to a professional, or “a person skilled in the art”. For example, if an alleged invention describes a tool made of stainless steel but the same tool made of cast iron was already available, presuming that changing the material does not affect how the tool works, this tool would be probably “obvious” to a person skilled in the art and therefore unpatentable.