A vehicle seat assembly includes an inflatable air bag and a housing associated with the air bag. The housing includes first and second housing portions that are moveable away from each other upon inflation of the air bag, and the first and second housing portions have first and second receptacles, respectively. The assembly further includes a cover material overlaying the housing and having first and second sections that are connected together at a deployment seam through which the air bag is deployable. First and second retainers are connected to the first and second sections, respectively, and disposed in the first and second receptacles, respectively. Upon inflation of the air bag, the retainers are configured to facilitate deployment of the air bag through the deployment seam.