A weight system for supporting a free-standing object comprising first and second upper panels, a least one side panel, a lower panel, and a closure system. The panels are joined to define an upper wall and at least side wall, with the first and second upper panels defining a fill opening in the upper wall and a container defining an interior chamber. The closure system is arranged to allow the container to be configured in a closed configuration in which access to the interior chamber through the fill opening is substantially prevented and an open configuration in which access to the interior chamber through the fill opening is allowed.