I found that the sanitizer units that cost less, about a $5 savings, do not fit correctly into my spa without this item. It was given to me when the spa was delivered and the cost was not mentioned but I was informed that I needed it as if I hadn't used it the cartridge would have slipped down into an opening and not be removable. . The delivery people stated they knew of no supply house in this area that even handled it but I could call their service headquarters. I went online and searched and Pool Supply unlimited was the only place I found this unit. I don't know if the cost was to much but felt that a backup was needed. I also know that items such as this wear out with time so another reason for my purchase. I cannot be happier with it as it is identical to the one I have in my spa now, however I have not even unpacked this one, it is my back up and if I do have to use my backup I will order another. If there had been any financial advantage, price discount, for getting more that 1 I would have as I am sure it will have a life of only a couple years based on my previous experiences.

I found that the sanitizer units that cost less, about a $5 savings, do not fit correctly into my spa without this item. It was given to me when the spa was delivered and the cost was not mentioned but I was informed that I needed it as if I hadn't used it the cartridge would have slipped down into an opening and not be removable. . The delivery people stated they knew of no supply house in this area that even handled it but I could call their service headquarters. I went online and searched and Pool Supply unlimited was the only place I found this unit. I don't know if the cost was to much but felt that a backup was needed. I also know that items such as this wear out with time so another reason for my purchase. I cannot be happier with it as it is identical to the one I have in my spa now, however I have not even unpacked this one, it is my back up and if I do have to use my backup I will order another. If there had been any financial advantage, price discount, for getting more that 1 I would have as I am sure it will have a life of only a couple years based on my previous experiences.