The connectors are decent and really a great value for so little money.  I have found many of these very inexpensive connectors from China to be of good overall quality. I am not sure the same can be said for the bulk wire/cable. 
I have several Viborg power cables, all under $150 and they spank many US-made cables selling for 2-5x the price. Their connectors are state-of-the-art and the wiring is pure red copper. Too many folks think if it's made in China it's crap. I can tell you that's crap. Price and quality are not inversely proportional with the Viborgs, they are very, very impressive.