Grades

Residential Grade is the least expensive.  It's primary purpose is decorative.  It performs well at defining boundaries and creating a landscaping back drop.

 

Commercial Grade is the most common.  It can withstand more abuse than the Residential Grade.  The rails are taller to provide more vertical stability.  It is recommended to have a 2.5" post. 

 

Industrial Grade has a 1" picket and 1-5/8" x 1-5/8" rail.  The posts can be 2.5" or 3" depending on your design and application.  This is a very strong product.