The Flux Observations: TOB: Transport Observation Package pane is on the MODFLOW Features tab of the Object Properties dialog box.
This tab is used to associate an object with a flux observation in MT3DMS. The flux observations are defined in the Manage Flow Observations dialog box. To associate an object with a flux observation, the user checks the check box for the appropriate observation in the table. The user may also specify a Factor which determines how much of the flux to include in the observation. If no Factor is specified, it will be set to 1 meaning that all the flux will be included in the flux observation.
See the Manage Flow Observations dialog box for a more extensive discussion of Factor.
Clicking the Add or remove flux observations button will display the Manage Flow Observations dialog box.