and move it within the tube so as to adjust the height of the overflow tube 15 when the adjustable overflow tube 15 is located at the desired height the locknut 13 is tightened tightening or turning the locknut clockwise locknut 13 compresses the radial seal 12 against the outside of the overflow tube 15 thus locking the overflow tube 15 to the first overflow tube 11 to hold the adjustable overflow tube 15 in relative position to the first overflow tube 11 the upper end of the adjustable overflow tube 15 is flared 51 such that it provides a larger surface area to admit water in the event of an overflow of water additionally the upper end of the overflow tube provides a gap 49 in the flared overflow tube 15 that provides a latching point for the refill tube clip 19 discussed below the gap 49 provides in general a flat surface 53 interrupted by a ridge 55 the ridge provides a surface for attaching the refill tube clip 19 preferably the various parts of the flush valve 9 and the overflow tubes 11 15 are injection molded using a suitable plastic such as abs trademark plastic or glass filled polypropylene however none of the above materials are considered a limitation of the invention a wide variety of other suitable durable and low cost materials for injection.