A hollow point is an expanding bullet that has a pit or hollowed out shape in its tip, generally intended to cause the bullet to expand upon entering a target in order to decrease penetration and disrupt more tissue as it travels through the target. It is also used for controlled penetration, where over-penetration could cause collateral damage (such as on an aircraft). In essence, the hollow point bullet has two interrelated purposes: to increase its size once within the target, thus maximizing tissue damage and blood loss or shock, and by remaining in the target to expend all of its kinetic energy in the target, some of which will be lost if the bullet continues through the target. Jacketed hollow points (JHPs) or plated hollow points are covered in a coating of harder metal to increase bullet strength and to prevent fouling the barrel with lead stripped from the bullet. The term hollow-cavity bullet is used to describe a hollow point where the hollow is unusually large, sometimes dominating the volume of the bullet, and causes extreme expansion or fragmentation on impact.