As a former resident of the PRNJ, I can tell you that anything that holds 15 or less rounds is OK. To my knowledge, there are no restrictions on who can own them. You can have them shipped into NJ, provided that you find someone willing to do so - many companies refuse to ship mags to NJ that are even close to the limit, on the theory that if you can jam a 16th round into it then they will also get into legal trouble.
Of course, if you were like me and didn't see anything intrinsically wrong with owning a stamped metal box with a spring inside of it, then you'd go to a Pennsylvania or NY gunshow and buy whatever the F you wanted to, for cash. I did it, and when I left NJ I had about 200 years of prison sitting 3 feet behind me in the car.
NJ sucks, and it isn't getting any better. I grieve for my homestate, which used to be a haven from the liberal Hellhole of NYC. Now it is just a suburban subsidiary of NYC liberalism.