For my purposes, this product worked great. We're not really into "heavy" bondage, nor do we have any fixtures from which we can engage in suspension play, so the tethers may not have taken enough of a beating to really test the upper limits of what they can handle. Nevertheless, when it came to keeping her tied to the bed, they got the job done. I didn't have to screw anchors into the wall, or my bed, or learn to tie fancy knots. For bondage fun with minimal prep time, these tethers were perfect. I was able to slip them onto the bed, slap the wrist cuffs on her, and snap her in before she knew what was going on. Others may have different feelings about this, but when it comes to bondage, I prefer to minimize the number of times I hear "no, wait, hold still", "almost had it that time", "are you done yet?" and "I can still get out." I get enough of that during ordinary sex.
The biggest downside to these tethers, for my purposes, is that I want another pair so I can restrain all of my girl's limbs at once. The only other substantive criticism I have is that the tethers would have been made much more versatile, and probably stand up to repeated use better, if the swivel snap was just slightly larger. If each snap was large enough to accommodate two rings, I'd hardly need another pair.