Hair density refers to how thick or how thin the human hair wig is. Density tells you the degree of thick and thin hair. When the value of density higher, this means the hair is thick, on the contrary, the lower density, the thiner the hair is. Density is indicated by the numbers of hair on each square inch of the head or wig cap. Medium density is 150% density which is international standard. Higher than 120% density is considered heavy density. 180% density is the thickest density, lower than 120% percent density is a lighter density. Most women prefer 150% medium density when they wearing full lace wig or lace front wig for a natural look and feel.
Measuring for yourself: A simple technique can be used to determine the difference between thick and thin hair in terms of measurement. If hair is long enough to be gathered into a ponytail, the circumference of the ponytail will indicate thickness. Thin hair has a circumference of 2 inches or less. Thick hair measures 4 or more inches around. Measurements in between are considered "medium density".
Free style refers to the ability to part the wig anywhere you want.