I bought a couple of them as I also bought some studio monitors for my audio interface. Considering that it is a fixed setup (I'm not going to move the monitors, cables, or interface anywhere alse), I though that the actual construction quality would not be that important.
The cables themselves are pretty thin and flexible, but appart from that, I would say they're durable enough if you're not going to move them or carry them around very often. In case you're a touring musician or you plan to gig often, then you may consider buying better quality, more robust cables.
Regarding the sound quality, they're very short and being balanced I highly doubt there's any kind of difference in sound to any other pair of more expensive cables. If you're building your setup and you're looking for a cheap (although fairly good quality) alternative for your balanced cables, this is a good option.
The cable is made of rubber, and the ends made of metal with some short springs that protect some lenght of the cable from being bent or unsoldered.
Overall I'm pretty happy with my purchase, I would recommend them to anyone, and I would buy them again without hesitation.