This island tub drain quickly and easily installs free standing bathtubs from above the floor. The drain attaches to 2 in. sch 40 pipe and mounts to a 2 in. p-trap in the floor for sewer gas retention. The drain also comes with a 2 x 1-1/2 in. reducer bushing to accomplish the same task in the smaller size. The drain easily mounts in the sub floor using a 3-7/8 in. (98 mm) hole saw. Drill through and attach with the included stainless steel screws to securely mount it in place.