This morning, Robert sent an email asking about the production time of 1,200 hydraulic check valves, which surprised me a little, because in the past 2 years, he normally just placed small quantity trial orders of hydraulic check valves. Robert is a purchaser of John Finlay company in Australia. We met 2 years ago. A batch of hydraulic tamping machine equipment of their company began to receive complaints again and again from the previous year. After inspection, it was found that the hydraulic check valve in the equipment did not maintain pressure. Robert contacted the original hydraulic check valve manufacturer to find a solution. The manufacturer advised that the working pressure and working frequency of the hydraulic tamping machine may be too high, resulting in frequent collision between the ball valve and valve seat of the hydraulic check valve, affecting the sealing effect. The only solution is to replace the leaked hydraulic check valve. Although replacing the hydraulic check valve is a heavy workload, Robert has no choice but to accept. The trouble is that 6 months later, the same problem happened again. The customer was very unhappy. The boss asked Robert to find a new supplier of hydraulic check valve immediately. Robert suggested purchasing hydraulic check valves from AAK to replace those unqualified ones, because the durability test of AAK hydraulic check valves was the most lasting among all of the samples from different manufacturers at the beginning. At present, there is an equipment installed with AAK hydraulic check valve, which has been used for 1 year but without any abnormality. The boss thought that the price of AAK was more than 20% higher and unacceptable, and asked Robert to look for a new manufacturer of hydraulic check valves. In the process of continuous screening, Robert selected 5 hydraulic check valve manufacturers to try their samples. Basically, after half a year, these hydraulic check valve samples had similar problems one after another. Robert was at a loss. He once again suggested to the boss to purchase AAK hydraulic check valves. After comparing so many hydraulic check valve manufacturers, none of their samples can be used for more than 1 year under this working condition, but the equipment installed with AAK hydraulic check valve has been used for nearly 2 years, and there has been no failure to maintain pressure. If the hydraulic check valve needs to be replaced every 6 months, the after-sales cost is too high, which has far exceeded the 20% higher cost of the hydraulic check valves. More importantly, it brings the reputation of unstable equipment quality to users. After listening to Robert's analysis, the boss approved AAK as the preferred supplier of their company for hydraulic check valves. It took Robert 2 years to persuade his boss to place a large order with AAK. He knew that the durability of AAK hydraulic check valve