Neutrik connectors, so it should be good. The connectors are metal, and you can easily open them up, should there be a need for maintenance/repair.
I like that they are basically two mono cables, linked together. You can unlink them as far as you want, turn them into two seperate mono cables if needed, and tie them back together again (with little velcro straps) should you want that.
I use them to connect an effects pedal to the FX-loop of my amp. So far, so good, I've only had for over a year, now. Mainly used them in the studio. I expect they will hold up a long time.
Thomann's service was, as always, swift and good.