or (very rarely) submachine guns in their vehicles for additional firepower. These are typically intended to be used when their use would be necessary or ideal compared to handguns, such as when confronting an armed or armored suspect, or when a handgun would not provide the range, accuracy, or rate of fire required for the situation, such as when engaging a suspect from a distance or in close-quarters combat. Less-lethal weapons Police officers often carry an impact weapon—a baton, also known as a nightstick. The common nightstick and the side handle baton have been replaced in many departments by collapsible batons such as the ASP baton, though some departments continue to use them either as an option or out of tradition, such as the Baltimore Police Department's wooden espantoon batons. One advantage of the collapsible baton is that the wearer can comfortably sit in a patrol vehicle while still wearing the baton on their duty belt. The side handle nightstick usually has to be removed before entering the vehicle. Many departments also use less-lethal weapons such as mace, pepper spray, and beanbag shotgun rounds. Another less lethal weapon that police officers often carry is an electroshock weapon, also known as a Taser. The handheld electroshock weapon was designed to incapacitate a single person from a distance by using electric current to disrupt voluntary control of muscles. An individual struck by a Taser experiences stimulation of their sensory nerves and motor nerves, resulting in strong involuntary muscle contractions. Tasers do not rely only on pain compliance, except when used in drive stun mode, and are thus preferred by some law enforcement over non-Taser stun guns and other electroshock weapons. Specialized weapons Most large police departments maintain special weapons and tactics (SWAT) units, police tactical units trained and equipped to handle situations such as barricaded suspects, hostage situations, terrorist attacks, and high-risk warrants that require greater force, specialized equipment, and special tactics that are unavailable to regular police officers. These units usually have submachine guns, automatic carbines or rifles, semiautomatic or pump-action combat shotguns, sniper rifles, stun grenades, smoke grenades, ballistic shields, door breaching tools, and other specialized weapons and equipment at their disposal. Some SWAT units are equipped with dedicated SWAT armored vehicles, trucks modified for police operations, or retired military vehicles acquired from the Law Enforcement Support Office. Others are capable of handling other non-combat-related tasks, such as the NYPD's