I didn't use these crossover cables to actually make an a/b crossover, but instead used them to attach female ends to some DMX light fixtures which are powered and controlled by cat5 cables. These worked exactly as planned, and were the only easy way I found to buy female rj45 connector attached to a cable.
I was very satisfied with these cables as well as with the many other items I've purchased from MonoPrice.com. This is definitely the best online source I've ever found for purchasing high quality ethernet cabling, cable testers, and associated installation tools & supplies at VERY reasonable prices.
PROS: These are very good, high quality cables for a surprisingly low cost! MonoPrice.com's online ordering service is also VERY prompt as promised!
I bought this extension cable despite not having an immediate need for it. I predict that this crossover adapter will stop being sold as more new equipment is capable of auto-negotiation. If you work for a company, as I do, that doesn't replace anything until it dies, be sure to get one before they disappear.
I love the idea of a crossover adapter for cables. Working with managed routers and switches, many have ports that are not auto-sensing, and when you're in a stack of cables and need something connected quickly, this works great. I was hoping for a smaller device, not 8 inches in length, but these are effective.