Don't Bother
This came as part of a set of multiple items from Swiss-Tech. I tested the glass breaker, multiple times from various locations, and it didn't so much as scratch the glass. The siren can be loud, but it's also very easily stifled in the manner you are holding it. Haven't tested the seatbelt cutter, but I'm guessing my knives are just as well suited. It's way to bulky to be on my key chain.

This is junk at ANY price
Not very well made; probably will not be at hand should you ever need it, unless you carry it on your keychain; it's really too big & bulky to carry on your car's keychain.
I bought one, tried it out as best I could, and eventually just rejected it to my junk drawn.

Too big and bulky
Too big and bulky for me. I think I would have rather had the Rescue-Me version of this item. I do think its more practical than the full-size hammer. The siren is not loud, and I wouldn't think to use it.

DO NOT TRUST
I just bought two of these one for myself and one for my wife. I have a friend who works in a junk yard and agreed to let me try them out, the first one I used shoved the rod through the plastic on the inside and the second popped out but did not have the power to break the glass. PLEASE do not count on this to save your life if you do buy one try it out several times before you trust it. The light would be handy though if you turned on the light it might help the rescue divers find your body!

A bit premature, as we haven't had to use it yet.
... Pulls from key chain with a jerk, but is on firm enough to stay there during an accident, I think. And hanging from your ignition, it's more likely to be within reach. Having something in your purse or glove compartment won't help you after an accident knocks the contents of the vehicle all over and your seatbelt has you trapped in your seat unable to reach the glove box.
... Haven't tested on auto glass, but breaker pin has a surprisingly good punch for not being difficult to push. A lot of tool punches are difficult to press in, but this requires minimal effort and punches hard with a very sharp point. Don't test it too much on hard material and dull the point.
... Flashlight is better than nothing, and sonic alarm ranges from powerful to pathetic, depending on how you're holding it. If you have to use the panic alarm, I fear you will not have your wits about you enough to keep the speaker uncovered and facing outward so the sound can travel. A scream would be more effective, I feel.
... It's right for the price, and really, having a light in a dark place can be invaluable. But since I was buying several, I only bought these for the women and to save money, bought these for the men, which are also easier to see in dim light.ResQMe, The Keychain Version of the Original LifeHammer (Yellow), Pack of 2