Our HOLLOW CORE Bi FOLD DOORS are for standard residential use or economy commercial applications. The standard features of these bi fold door sets are 1 Â¼ one piece soft wood stiles (not finger jointed), 1 7/8â€ top and bottom rails, luan backs, non-mortise hinges and honeycomb core. All our Bi Fold door sets include all necessary track and hardware. There doors carry our one year warranty for interior applications. These Bi Fold door sets are well suited for commercial tenant build-out or commercial retail jobs where cost is a primary concern along with quality. These doors are available 1 3/4" or 1 3/8" thick and as hollow core or solid core. Additionally special sizes and veneers are also available. Please contact our sales office directly for your custom size door needs.