This Raypak component is a specially designed mechanical device known as a bypass spring. It is primarily used in pool and spa heaters to regulate the flow of water through the heat exchanger. The spring's function is to open or close the bypass, depending on the water pressure. When the water pressure is low, the spring compresses, allowing more water to bypass the heat exchanger. Conversely, when the water pressure is high, it expands, reducing the amount of water that can bypass. This mechanism ensures optimal performance and efficiency of the heating system by maintaining a balanced flow of water through it. The product is made from durable materials to withstand constant changes in pressure and temperature.