The 1600 Brine Valve Short Stem is commonly used in the Fleck 1500 and 2500 models. The piston assembly ( part # 60029 ) should be replaced if the brine refill never stops ( valve is stuck ).The 1600 ( or 3/8" tubing size ) valve is normally used on softener tanks up to 16" in diameter. And typically used on the Fleck 2500, but we have seen used on 2750, 2850, and even some 2900 valves.Larger commercial valves will normally use the 1700 ( or 1/2" tubing size ), part # 60034 ( see our part 346003424 ).NOTE: The Brine Line Flow Control portion ( 6002025 or 6002050 or 60020-100 ), is sold separately ( or as option with this item ),