Sapphire units in general come with books and other things, basically codes come with out of game stuff. I won't buy the books, i will remain hopeful that they one day appear on nutaku as well, as i still see that as my main account that i spend money on. They have had codes for non-units in the past though that were totally free.

That said, there is a code that will come bundled together with https://www.hlj.com/product/GSC90099/Act and since i found it cute i had to pre-order it :P

That said, what Yoxal said is true - between gold and plat.