I purchased some branded toslink cables a while back. They were really thick and looked heavy duty. BUT, I had disconnection issues all the time because the optical ports on several devices cannot handle the weigth of the cable.
I replaced all the optical cables with this one and everything is back to normal. They are light, so they don't stress the optical ports, but the same time their material looks very durable.
I use them to connect an RME Digiface USB with Apogee AD16X + DA16X.