I was going to rate these 1 star until I figured out what I was doing wrong. These work great IF you use them correctly.

First, make sure to get the correct ones. The bad reviews seem to be mostly related to using the wrong type.
Second, make a good connection THE FIRST USE. These make the best connection the first time. While they can be reopened and reused, I try not to consider them reusable because the connection isn't as strong on reuse. Make sure everything is aligned and with the proper wiring order the first time.

Steps for Wire to LED strip versions:
1. Insert the tip of your needle nose pliers into the connector and use a blade to open the side clips. They are very difficult to open by hand.
2. Tear the backing paper off adhesive LED strips for 1/2inch of length
3. Insert the LED strip until the copper tabs are centered over the sharp contacts in the connector. DO NOT shove the strip in as far as it will go, it won't work.
4. Close the LED cover until the clamps click in place. The LED side can usually be closed by hand.
5. Separate the ends of your connecting wire back about an inch and align to connector. Make sure the wires correspond to the proper label on the LED so you don't blow your power supply.
6. Insert the wires far enough to pass over the sharp contacts in the connector. Again, DO NOT shove the strip in as far as it will go, the cover won't be able to close all the way and the wires won't get pierced.
7. Close the wire cover as hard as you can by hand, checking to make sure the wires are still in the right place. You will need a pair of pliers to close the cover the rest of the way until the clips engage.
8. If you so desire (I do), wrap some electrical tape several times around the connector. I've only really needed to do this on connectors that I reused and broke the clips on, but I like knowing it can't get dropped or knocked loose.

Using these the right way is a bit of a pain the first couple times, but they're far easier than soldering. I haven't found another connector that even comes close to this one in terms of security. Minus 1 star because I have to separate the wires and align them. This should have been designed to natively accept a standard four-wire without separating.

As described. Good Bargain. Thank you

What a great concept. Easy to use. Great. THX

Beats soldering all these connections

I love this quick connector. It makes so easy to connect my RGBW Strips to the extended 5 pins wires for my kitchen lighting. (Note: this one fit the standard 5 pins strips....not for smaller 5 pins strip)