The Territorial Support Group (TSG or CO20) is a Central Operations unit of London's Metropolitan Police Service (MPS) consisting of 793 officers. It specialises in public order containment, among other specialist policing. The TSG is a uniformed unit of the MPS that replaced the similarly controversial Special Patrol Group in 1987. TSG units patrol the streets of London in marked police vans; officers can be identified as TSG from the distinctive "U" in their shoulder numbers.