Building interior or exterior doors has never been easier than with the help of these 2-piece Door Making router bit sets. Building a 1-3/8" thick interior, or 1-3/4" thick exterior facing door has never been easier. With the help of these 2-piece Door Making router bit sets, you'll be able to make the rails and stiles necessary to make solid wood doors for your very own home. Each Infinity Tools Entry & Passage Door Rail and Stile set includes two router bits. Use the included 1/4" kerf slot cutter to increase the width of the tongue and groove from 1/4" for interior doors to 1/2" thick for exterior doors.