its a fucking rip off. you're better off buying perms rather than those.
never bought nx and prob never will
It took me 30 keys to get P90 SE LE and MP5 RAS LE
My brother and I spent like 50k on Keys when we first started CA, The best thing he got was a 90 Day MP5 RAS, And the best thing I got was a 1 day L96A1 Arctic Wolf.
But, I heard that the higher your NX Grade is, The better chance you have of getting a Permanent gun from a Black Hi Sec, Also heard that the more you buy at once, The more chance you have to get a Permanent gun from a Hi Sec, May just be a rumors. But at the time we redeemed ours we weren't even a Bronze. (Yes, First time we bought NX.) If your NX Grade is Gold+, Definately buy a few.