1 HP version used on Softub Spa models. ALL Softub pumps are 1 HP, there is no 1.5 HP as this would not run on 15A circuit! It may be advertised as 1.5, but in actuality is truly 1 HP. Threaded inner tube has plastic threads now. May shatter when trying to remove from motor shaft to replace shaft seal. Apply small amount of silicone grease to shaft collar tube to slide shaft seal down over it against back side of impeller.