I have been using the Porter Cable 7424. My wife helps me detail and likes using the PC. I saw an opportunity to upgrade. So she can use the PC an I'll use the Flex.
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I have not used 845 yet but I like the durability of 476s. I applied it to a Dodge Ram in early November and it lasted until the first week in April when I detailed the truck again. It is a daily driver and sits out 24/7 here in PA. Collinite 915 is my favorite paste wax. I really cannot compare...