Excellent  product. I have owned my Tuff Spa for about a year now. I live at 7000 feet in the mountains so I brought it indoors. I contacted Tuff Spa's to ask if the Del MCD-50 ozonator was compatible with my spa. As to not confuse or paraphrase, I will quote the email exchange. In response they stated: \"You will have to use a Balboa ozonator. You can not retro fit another unit with this equipment.\". So, I purchased it. One day later I emailed him and asked: \"As long as the voltage & plug-types match, why wouldn't it work for ozone? It just turns it on and cycles?\" His response: \"I don't see why it wouldn't work, but I don't wanna say it will and then it not work.\" When asked why he didn't tell me that in the first place but instead said: \" You can not retro fit another unit with this equipment\", he did not respond. When I asked for a refund and refused the package when delivered he immediately stopped emailing me, and I had to contact Chase bank. They have still not refunded. Although the product it a good one, the salesman \"Do*g\" was problematic, and then \"poof\", vanished when things did not go his way. I installed the Del MCD-50 Ozonator which he stated: \"You can not retro fit another unit with this equipment.\"  and the Del is working just fine. When first contacting him, I had asked if this model would work... So, you decide. I will update this post when, if, and how long it takes to get my refund or other shenanigans that may develop. It is what it is but I'm pretty disappointed when I have to go through this - it makes no sense, is unnecessary, and could have been handled so much better.  A negative Yelp review over a hundred dollar ozonator ? go figure....