These premium quality cutters are used for making longer tenons to add strength to your interior (1-3/8" thick) or exterior (1-3/4" thick) doors. Use the 91-522TC in conjunction with our Ogee 91-522 set and the 91-525TC with our Shaker 91-525 set. The matched router bit set makes a standard 7/16" width tenon but, with these cutters, you decide the tenon's width. For heavier doors you may want a wider tenon. If you already own our 91-522 or 91-525 two-piece set, the tenon cutters are the perfect companion router bits to expand your door making potential.