This is the small cogged belt that is used by the Hoover hand sized turbo tool with a roller brush that comes attached to the front of some Hoover windtunnel models.
Hoover geared belt 38528037 fits the following hand tool models:
49129044, 49129018 and 49129019
49129024, 49129027 and 49129039JI.
Single belt replacement made by Hoover.