Flexible tubing in place of the rigid PVC overflow pipe allows the overflow tubing to easily bend over from a misaligned drain pipe to the overflow hole of the tub1-1/2" -11-1/2 NPSM (coarse thread), 1.865" major diameter (outside thread diameter, 11-1/2 threads per inch. Quickly and easily add a beautiful finish to your MAAX romance freestanding tub with this waste overflow. Utilizing flexible tubing in place of rigid PVC overflow pipe, allows for the overflow tubing to be easily maneuvered around a misaligned drain pipe to the overflow hole of the tub.