As always monoprice is awesome, but unusually this product is not.
Half or so of the batch I received are faulty. Tests bad on my cable tester. First bad product i've received from monoprice and i've been a regular customer since 2007. Just posting to warn future shoppers of this particular item.
I ordered 14 of these for a home networking project. As a result I spent a solid week diagnosing wires with a wire tester, wondering if I bought bad cable, before finally isolating the issue to /8/ of the 14 keystone couplers I bought. Six are currently still in service, but when I get around to it, I am removing every single one and tossing them out.
ANY touch or manipulation of a ethernet cable plugged into one of these, on either side, can cause a temporary disconnect at best, to complete failure of the keystone at worst. This makes diagnosis very frustrating they can literally work fine while you are testing them in one position, then stop working when you plug the tested connection into the device you want to service. Then you start all over again and tear your hair out.
Due to my experience with this product I am never going to buy a keystone product from Monoprice again. Cables, certainly. Other products? YES! Keystones? NO. Not worth the loss of time over such a cheap part. Hopefully buying something twice or thrice as expensive from a competitor is the way to go.
PROS: Look nice when fitted into a face plate. The black colour lets me easily tell them apart from telephone jacks or cat 5 jacks.
CONS: Unreliable. Flimsy. Easy to break. Wastes time.
Buyer beware, these things are flimsy. You get what you pay for.
PROS: Well, it worked until I decided to relocate the router. Then lost connection.
CONS: Isolated the connection issue to this coupler. When I took the wall plate off and tried to disconnect one of the cables, the thing broke apart in my hand with very little pressure. One of the internal leads broke off as well.