Build Custom Divided Light Windows & Doors With Our Matching 2-Pc. Bit Sets. The bits also produce perfectly matched rail and stile parts for 1-3/8" to 1-5/8" thick custom-built French doors. Being able to rebuild windows or interior french doors without having to go to the salvage yard is very worthwhile. Our 2-Pc. Window Sash Jr. router bit is for making thinner sashes between 1-1/8" and 1-1/4" thick set is and designed to mill sash parts that offer elegance and strength to your custom wind or or door project. The bits also produce perfectly matched rail and stile parts for custom-built French doors.