I use these extensively, Had many a jr spectrum break at the connection. I also strain relief and put dab of shoe goo e6000 at the wires on the connector. heavy duty and very worth the price. never had one fail.
The black and yellow wires were swapped from end to end on one of two of the connectors i purchased. I connected it before noticing this and it caused my receiver to not work and become warm. This could have shorted my receiver, causing serious damage. Luckly it still works.
*Update to my previous review: Amain sent me a replacement and I have had no further issues with this product. Although, for the cost and quality I would recommend the Spektrum 6'' extension as it comes with two in the package.