What are Knife Scales?

What are knife scales?  Knife scales are either wood, metal, or resin pieces of material that are used to construct a knife handle.  The two pieces of material are placed on both of the metal tang and secured with either pins, rivets, or glue.  After the material is secure the material is shaped into a handle than sealed for durability. 

What are knife scales? Exotic Knife Scales | Rundle Woodworks