I like the quote "Custom molded shape" = a contradiction as anything custom is one off, and the "Coated with waterproof resin"
6.15kg (and they are usually optimistic) is a lot of weight for a 5'8''.
I think custom can also refer to "something specific to a gruop", not necessarily a one off kind of thing. Ie it is designed for kiteboarding..if the ad is directed to kiters.
According to the English dictionnary : custom-made, custom,
made according to the specifications of an individual.