Genuine Balboa M7 Stainless Steel Flow-Through Replacement Hot Tub Heater Assembly using dual sensor M-7 technology. Has 2" (nominal) fittings which measure 2-1/4" actual inside diameter. For 1.5" plumbing, use PVC reducer bushings. For Balboa VS, EL, TS, GS, and BP Series control systems. Latest updated version. Older units (obsolete) had white unions. OEM # 58117. also replacement for C2400-0807, 58032, 58103, 58104, 58148, 26-0807-5S-KS, 26-0807-5S-K, C2400-0807-TPS. Made in USA. 1-year manufacturer's limited warranty.