Horn Flush Concentrate 4oz Refill Horn Flush Concentrate 4oz Refill makes 16oz Environmentally friendly and water-soluble solution is swished into the instrument to loosen built up dirt, grit, and food particles. 4oz. bottle of Horn Flush concentrate is enough for up to 4 flushes! (2 low brass). Low cost solution to keeps your horn clean and ready to play. And it will smell great too.