The Laing Square Back D1 Heater is a 4kW low-flow spa heater designed for select Dimension One Spas (D1), Bay Series, and Artesian Spas. Featuring a square-back design, it fits seamlessly into systems that use Gecko MSPA controls and low-flow circulation pumps. With titanium heating elements, it offers excellent resistance to corrosion, making it ideal for long-term use in demanding spa environments. The unit includes multiple built-in safety features, such as a thermal cutoff switch, hi-limit probe, and reed switch flow sensor, ensuring both reliable performance and user safety.