See "pros" above. They also come with 2 little nylon ties, and the base has a place to tie the wire down with that tie (If the wire insulation is too thin, you can tie the wire with only one side of the wire "support" in the base - easier to see than to explain). I recommend these. Inexpensive and they work well.
PROS: I like these a lot. They seem to work fine with branded (Leviton, for instance) and also generic keystone jacks like those you get here. Well made and easy to use. I like the removable inserts that you can snap the jacks into, and then slide the jack+insert into the base. It's also fairly easy to remove the jack from the insert - some boxes make this very difficult. These come with both screws and stick-on pads. I usually use the stick on-pad plus one screw (along with a wall-anchor if in drywall).