The Special Duties Unit (Abbreviation: SDU; Chinese: 特別任務連; nicknamed 飛虎隊, or "Flying Tigers") is the elite tactical unit of the Hong Kong Police Force tasked with countering terrorist attacks, hostage rescue, underwater search and recovery, and tackling serious crime involving firearms.The SDU is a subdivision of the Police Tactical Unit which is part of 'A' Department (Operations & Support).The SDU is based at the Police Tactical Unit Headquarters in Fanling.