T-Mobile is now offering the 64 GB iPhone 6 for the cost of a 16 GB iPhone. The carrier, for Cyber Monday, is offering a free upgrade which means checking out with a 16 GB iPhone 6 will immediately result in an upgrade to the 64 GB version. A similar deal is being offered for the iPhone 5S and 5C.

The carrier says a 32 GB iPhone 5S will become 64 GB and the iPhone 5C 8 GB will become 32 GB.

T-Mobile's upgrade deal for the iPhones can only be had online and the carrier also warns that its inventory is limited.