For example, one method for gases’ being packaged is metal cylinders. On the other hand, liquids can be packaged with the use of metal pails. Another physical feature is the ability of the product for the elements to be withstood. It is possible to expose coal to rain but piles of salt cannot be exposed. There can be revealing of few items to conditions of freezing whereas others can’t. Another physical feature is density of product (per volume weight) by which the conditions of packaging can be affected.