to 14 days in length with most of the emphasis placed on physical endurance. In 1998, this changed to a basic four-day selection course with more emphasis on mental attributes than physical ones. Those who successfully passed the basic selection course were given a five-week build-up course followed by a week-long advanced selection course. The course concentrated on weapons handling and use, elementary close-quarter battle, camouflage and concealment, physical fitness, observation and commentary, first aid, and map reading. For the period 1998–99, 44 officers applied with 14 selected. Equipment and weapons SDU officers deploy in Crye Precision G3 combat dress of various camouflage patterns depending on the environment. Officers may also deploy in plain clothes during a rapid response when there is no time to change. Armor and accessories include Ops-Core FAST ballistic helmets with attachable night-vision scopes and ear protection, MSA Advantage 1000 CBA-RCA respirators, and Dräger LAR V rebreathers (for tactical diving). Unlike many similar units around the world, most of the SDU officers do not display the word "Police" on their uniforms. The SDU mainly uses firearms manufactured in the United States and Europe, and its latest equipment primarily include the Glock 17 handgun, the HK MP5 submachine gun, and the SIG Sauer SIG516 assault rifle. Shotguns include the Remington 870 and Benelli M1 Super 90. Snipers rifles used are the Remington 700, Knight's Armament Company SR-25, Accuracy International AXMC .338, Accuracy International AS50 and SIG Sauer SSG 3000. In 2020, the United States, the United Kingdom, and the European Union, placed restrictions on the sale of military equipment to Hong Kong following the passing of the national security law. As a consequence, an order of 1000 replacement MPX submachine guns and SIG516 assault rifles for the SDU and other units placed in early 2021 was cancelled by SIG Sauer, and the Hong Kong police will need to source firearms elsewhere for all units, including the SDU. The SDU has several land vehicles including the Mercedes-Benz Unimog U5000 armoured personnel carrier, the Jankel Guardian Tactical Intervention Vehicle based on a Ford F-450 chassis, Mercedes-Benz Vario van and Man LE14.224 truck. The SDU has two types of watercraft to support its maritime operations; the FB Design RIB high speed interceptor and Zodiac inflatables. The Government Flying Service provides aviation support with Eurocopter AS332 Super Puma and Eurocopter EC155 helicopters. Known operations 1992: During a raid, the Unit was