QJ is a new type of 4x4x4. It is very similar to the Mefferts brand, only it is alot more "fluid" like turning. When you buy it, it's already very good and doesn't lock up at all, but with a bit of use, it get's even better. You can also get a smaller 6cm version of the QJ 4x4x4, which may be better suited to cubers with smaller hands. This is a very good cube and it is a probably the best 4x4x4 on the market.