That beyerdynamic is all about quality can come to no surprise to anyone who has ever laid hands on some of their designs even the packaging is well made.
The rest of the bundle is quite neat. You get a manual, USB sound card, 1/8" to 1/4" adapter.
Beyerdynamic include a USB sound card with each set of MMX 300s. The USB sound card is nowhere near as well built as the headset itself, and does not feel that sturdy.
Like most of the other details on the MMX 300s the mini-jacks are of a very high standard. The cable also seems thicker and better assembled than those featured on Razer and Sennheiser headsets. A 1/8" to 1/4" adapter is also included in the bundle if you wish to use the headset with a headphone amplifier instead of the headphone outs on your sound card.