This is a unique product, since it is a rugged, female RJ45 Cable Plug, that can be connected to Neutrik EtherCon cables. I would say they are pretty durable, from the look of things. You can use this to create Cat extension cables, and replace the Neutrik NE8FF coupler.
The quality control is a bit lacking, however. On one of the ones I ordered, the Strain relief part looked like it had been squished hard by some pliers. The packaging was not even opened yet.
All in all, I would say, that this is a great product, which could do with some quality control before shipping.