Imperial Brown Heavy Gauge Floor Grilles are for use in commercial and residential areas. These grilles are extremely durable and has over 75% free airflow space. To determine the size of floor grille you need, always measure the actual hole opening size in your floor and base your order off that. For example, if the hole in your floor measure 4" x 12" then you will want to order a 4" x 12" grille. These grilles have an overall dimension of 1 13/16" larger than the listed size - therefore the 10" x 16" has an overall dimension of 11 13/16" x 17 13/16".