Jack,
The Flush-Tite closet flange can be glued inside of a 4" pipe, or glued outside of a 3" pipe. If the pipe being used is a 4" pipe, it will need to be cut flush or even slightly subflush with the floor.

Another product that can be used on 4" pipe is the Compression closet flange. These tighten down with stainless steel screws with an adjustment range of 3" to the riser.

Glad to help Jack.
Terry

• Drains - Level-Fit Closet Flanges (click here)