The information provided HERE at Gadgetsgo is very accurate. Be sure to do all your calculations first. I bought a unit elsewhere. They did not give all the right info and it does NOT work properly; it was sized too small based on their bad info. In the future I will get one of these units the right size from here.
I have to acknowledge the service of the company is excellent. But especially I have to highlight the service provided by the gentleman who assisted me in the buying process. This gentleman was very friendly and very helpful. The delivery service super fast. Related to the product is excellent, I have one in my house and this is for my mom. Overall I am very grateful for the whole process.