To know how to choose a good quality human hair product,you must know some basic knowledge about our hair.
Human hair shaft is consisted of three layers: cuticle, cortex and medulla. Cuticle is the outermost layer of a hair,which looks like layers of overlapped roof tiles .It protects the inside of the hair shaft from damage.All cuticles are facing the same direction when the hair is under heathy condition and has not been chemical treated.
