Stockholm Open (SO) is an annual tennis tournament in Sweden that is part of the ATP Tour's 250 Series. The tournament features both men's singles and doubles events and is organized by the Royal Lawn Tennis Club (KLTK), Stockholms Allmänna Lawn Tennis Klubb (Salk), and the Stockholm Tennis Federation. Stockholm Open has been played on hard courts at the Royal Tennis Hall since 1969, except for the period between 1989 and 1994, when it was held in the Globe Arena. The tournament is traditionally held in October and November. In 2020, the event was canceled due to the Coronavirus pandemic.
https://en.wikipedia.org/wiki/Stockholm_Open