General description Square Thermal Bladder designed for 6-person square spas, specifically compatible with all 4 + 2 models. This bladder effectively retains heat when the spa is not in use and allows rainwater to flow off the spa cover, ensuring optimal performance and longevity. Technical specifications Compatible with 6-person square spas Designed for all 4 + 2 models Not suitable for smaller Mspa 4 + 2 models