This 6500-310 Smart Low-Flow Heater Assembly is compatible with 1995+ Sundance/Jacuzzi Spas 650-850 & 880 Series with Low-Flow Heaters. It is also used on 2015+ Jacuzzi J-400 & J-500 Spas. 3 The Smart Low-Flow Heater Assembly is made of high-quality steel, copper, rubber and plastic.