Cheat pack or am I naive?

I bought the Christmas Lights at the hardware store. The printed package is an icon which indicates that the chain is 15 m long. Including a symbol that the supply line is 10 m long. Hence, in my opinion, that the light curtain is 15 m long. The chain including the supply measures a total of only 15 m, the illuminated part is 5 meters long. But the price is much too high. Sure, if you look closely at the icon, you can see a male and think that it is the total length in the 15m, but I think the company implying intention much more content than is actually present. So beware, who buys only one chain, can thus more than decorate his tool shed in the garden.