Basically an ATH M50 with the long awaited detachable cable. It ships with 3 different cables: 4 foot straight, 4 foot coiled and a 9 foot straight. However, you have to use Audio Technica cables since it has a twist lock mechanism. If you are looking for good quality audiophile/studio headphones, these are great. They are slightly more expensive than the original M50s but definitely worth it. On the other hand, if you already own the M50s, it is not worth upgrading to the M50X.