I used two of these couplers to connect and extend ethernet connections to my Roku and HTPC using  T Adapters Cat5e 2M/1F - 6 inch and  3FT Cat5e 350MHz UTP Ethernet Network Cable - Black . Everything worked flawlessly.
It works without any delays. If you need to put to good use your bundle of short Cat5 cables, buy about three of these couplers. My one extra coupler saved the day when I needed to extend a cable from my router to reach my new Wi-Fi-enabled printer across the desk (for the initial network setup).