GRID is a special field unit which is a part of the International Temporal Enforcement Agency. The acronym stands for 'General Response Investigation Department' and consists of agents not assigned to any particular team.
As one of her first acts as director of the International Temporal Enforcement Agency Sonia Castillo created GRID. The idea behind the move was to get the ITEA some extra field agents who could be sent to investigate possible incidents by themselves if the potential threat was considered low and send in teams to support them as needed. Likewise GRID agents can also be attached to existing teams for single missions if they require additional support but not that of another team. Michael Bradford was made the head of GRID.