It is most commonly associated with entrance wounds and is a mechanical defect due to a projectile's penetration through the skin. It is caused by a temporary over-stretching of the skin surrounding the projectile's point of penetration. Like all skin abrasions, the abrasion collar tends to dry out due to scraping away of the skin's outer layers and the collapse and dehydration of the underlying cells; it therefore becomes easier to discern with time.[1] This defect is most often seen around rifled firearm entrance wounds due to the striations or grooves in the bullet's surface caused by the rifling on the inside of the weapon's barrel; however, certain other high-velocity projectile wounds can also have the same effect.[2]