Others say...

"laptop lock with combo changes on its own"
Targus laptop lock with combo lock can change combonation on its own. I am in a dorm and decided to keep my laptop locked while I was not in my room. One day I could not get the combo to work. When I called Targus customer service they told me sometimes the combo slips on its own that I needed to try combos with surrounding numbers to the combo I had set weeks ago. It took hours of work, but after many tries found that the last combo digit had changed by one number drop. I am now going to purchase a lock with keys-never again will I use the combo lock.

"horrible! got stuck with correct combo"
Do not get this, it got stuck in my new macbook pro...and the combination was correct! Would not come out. Look elsewear.

"There is a newer model than the one in the photo: It's Great!"
I travel with my notebook in my backpack. I have had three of these things. You have to read the instructions to set the combination correctly!
They all have worked well and they NEVER have changed the combination on me spontaneously!
The newer model has the same features but uses AAA bats and not a 9V which the old one used. It is thiner than the old model also. I like the blinking red light when ever I arm it. I run the cable through my zipper on my backpack and leave in strapped to the desk or chair in my hotel room. It creates a shrill LOUD alarm (if you set it for this feature) when the unit is moved. There are two sensitivities. You can set it to only alarm if the cable is cut. Yes you can cut the cable with a good set of wire cutters...so it would not stop anyone determined to take your notebook from you and had strong intentions to do so. It will stop someone from just grabbing it and trying to run.
I also really like the little gadget in the photo...(lower right hand corner of photo) it fits into the security hole of my notebook very snugly. The cable of the Defcon can go through the hole of this gadget and you can just lay it next to your notebook and it will start to "scream" as soon as the notebook is moved (it does give you a ~15 second warning before "screaming" with a loud CHIRP sound, so you can disarm it. Go to Targus website and check it out. I don't work for them. I do believe they sell a quality little alarm. It is not Fort Knox, it is a lot better than nothing. Blinking light and siren deters the common dumb criminal (not on drugs or really crazy)from taking your computer. It's should be just one of a series of methods you have to secure your notebook, not the only one.
It's nice for travel. You can even hang the thing on a door knob and know if someone opens the door. It's a motion alarm with a blinking red light. The number of blinks tells you how it is armed. I recommend it.

"Mixed UP Reviews - Try This."
Not one single review here is about the actual item for sale. When I clicked on the product reviews for this item. The item is the Targus PA460U DEFCON Authenticator - Black [Electronics] Which in fact has nothing to do with combination locks, cable locks, Or for that matter any kind of locking device other than a programed security device which locks down your computer so no one can enter your files without you being present. Unless of course they have the same finger print as you. It can also work for more than on computer at a time if for save you have two linked together in your network and prefer you children (example) or whomever to have acess to your computer when you are not present. All I can say is that mine works great and I very happy I have one.

"Lock jammed, so I had to break it off"
I just finished breaking this lock off my laptop because it somehow jammed. My laptop was securely locked in my hotel room, keeping even a person with the combination from removing it. After a couple of quick blows with a ratchet handle, the lock itself broke apart. Once I took the end off the lock, it popped right off the laptop. See my photos above of the smashed lock.

When I bought this, I joked to my buddy that it would now take a thief 30 seconds longer to steal my laptop. If only I had realized how right I was. The only reason I spent half an hour trying to remove it was because I was trying to save the lock. I'll call the manufacturer to ask for a refund tomorrow. If they don't give me one, I'll take it back to Staples, where I bought this just six weeks ago.