capable of protecting the wearer from small caliber handgun and shotgun projectiles, and small fragments from explosives such as hand grenades. Metal or ceramic plates can be used with a soft vest, providing additional protection from rifle rounds, and metallic components or tightly woven fiber layers can give soft armor resistance to stab and slash attacks from a knife or bayonet. Soft vests are commonly worn by police forces, private citizens and private security guards or bodyguards, whereas hard-plate reinforced vests are mainly worn by combat soldiers, police tactical units and hostage rescue teams. A modern equivalent may combine a ballistic vest with other items of protective clothing, such as a combat helmet. Vests intended for police and military use may also include ballistic shoulder and side protection armor components, and explosive ordnance disposal technicians wear heavy armor and helmets with face visors and spine protection. Limbs Medieval armor often offered protection for all of the limbs, including metal boots for the lower legs, gauntlets for the hands and wrists, and greaves for the legs. Today, protection of limbs from bombs is provided by a bombsuit. Most modern soldiers sacrifice limb protection for mobility, since armor thick enough to stop bullets would greatly inhibit movement of the arms and legs. Performance standards Due to the various different types of projectiles, it is often inaccurate to refer to a particular product as "bulletproof" because this suggests that it will protect against any and all projectiles. Instead, the term bullet resistant is generally preferred. Standards are regional. Around the world ammunition varies and armor testing must reflect the threats found locally. While many standards exist, a few standards are widely used as models. The US National Institute of Justice ballistic and stab documents are examples of broadly accepted standards. In addition to the NIJ, the United Kingdom's Home Office Scientific Development Branch (HOSDB—formerly the Police Scientific Development Branch (PSDB)) standards are also used by a number of other countries and organizations. These "model" standards are usually adapted by other countries by following the same basic test methodologies, while changing the specific ammunition tested. NIJ Standard-0101.06 has specific performance standards for bullet resistant vests used by law enforcement. This rates vests on the following scale against penetration and also blunt trauma protection (deformation): In 2018 or 2019, NIJ was expected to introduce the new NIJ Standard-0101.07. This new standard will completely replace the