Stegmeier Flowmaster A/T Commercial FLO-AT4.5C 10' x 4.5" Deck Drain Clear. Flowmaster A/T commercial deck drain is a removable top drain that features an aluminum top. This product also features a double wall base and a snap in top. When installing this drain the tops are staggered past the joints making the joints very rigid. Because the aluminum tops are removable this drain is easy to clean and the tops can be replaced if ever damaged. It is recommended that you drill and pin (3/8 Inch rebar) the base at 3 ft intervals to stabilize against any movement in the concrete slab. Flowmaster A/T is used on many commercial swimming pools and indoor pedestrian traffic areas.