Alpine SwissMen's RFID Harper Money Clip Front Pocket Wallet Leather York Collection One Size Smooth Finish Black

Q: Could I put this in my back pocket comfortably? I usually put my cell phone and keys in my front two pockets, so I don't have room for it up front.

Yes and no if you put to many cards in there then it won't feel comfortable but like me only about 5 cards and cash it feels fine in back pocket .

Q: has anyone reported problems with their cards due to the magnet?

I've had a similar magnetic clip for years (it's worn out so I'm looking for a new one). Never had an issue with credit cards demagnetizing, but have had several issues with magnetic hotel key cards losing code, so now I always keep hotel key cards in a different pocket.

Q: How many cards will fit in the 4 slots?

Hi Joe:You should be able to carry 5-7 cards. I am going to link to another product page of this same item which comes without the RFID blocking you can see more of it's reviews for better guidance. It is the same size just without the RFID feature.http://www.amazon.com/Genuine-Leather-pocket-wallet-magnet/dp/B00N6I515M/ref=cts_ap_3_fbtThanksAlpine Swiss Amazon StoreCustomer Support