These are the AN8 to 3/8 Male NPT fittings@DavidR8 The photo on the Amazon.ca site shows the connectors for what I am guessing is flared soft copper tube? The Derale web site says the inlet and outlet are -8AN size which I believe is 1/2" copper.
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You have some sort of black coupler first and then the brass one down to 3/8" which I'm guessing is a compression fitting? Did the cooler come with the shiny black coupler or did you have one or order one from somewhere?
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