This dataset contains a SQLite database containing flexibility service data for the latest flexibility service (Tranche 5B – summer 2021). The database also contains DFES scenario based signposting for flexibility services. This data set is displayed on the Network Flexibility map on the NGED website and Flexible Power website. SQL queries are provided to extract data from the database in conjunction with example extracts. The SQL queries list: * Which primary substations are associated with which Constraint Managed Zone (CMZ) for Tranche 5B – summer 2021 flexibility service tender; * Which postcodes are associated with which Constraint Managed Zone (CMZ) for Tranche 5B – summer 2021 flexibility service tender; * Which CMZs are open for the Tranche 5B – summer 2021 flexibility service tender; * CMZ availability windows for the Tranche 5B – summer 2021 flexibility service tender; * CMZ utilisation volumes for the Tranche 5B – summer 2021 flexibility service tender;