Worked great! I had an existing hardwood floor that had previously been pushed into carpet. The old plumber just cut the bottom out of the tongue. This bit allowed me to make a groove in this floor so I could use a piece of spline to firmly connect my new floor to it. The transition is so fluid that with your eyes closed you can't even tell where the new and old floors meet. Beautiful, solidly built piece. It took less than 30 seconds to cut the groove, but it will be flawless for a lifetime.