These extended tenon router bits are used for making longer tenons to add strength to your interior (1⅜″ thick) or exterior (1¾″ thick) doors. Use the 91-522TC in conjunction with our Ogee 91-522 set and the 91-525TC with our Shaker 91-525 set. Our matched router bit sets make a tenon 7⁄16″ long, but for heavier doors you may want a longer tenon. These cutters allow you to decide the length of the tenon. If you already own our 91-522 or 91-525 two-piece door making set, the tenon cutters are the perfect companion router bits to expand your door making potential.