Just on a side note, if you do have to use a tool like the Res-Q-Me to break a window, make sure you've got some sort of protection on your hands/arms. I've used one a few times and it's really easy to slice the heck out of your bare hand/arm in the heat of the moment. (With the one I keep in my car, I also keep a pair of simple work gloves in the same spot.)

Also, if you aren't wearing glasses, it's best to either close your eyes or turn your head away while using the tool, as glass can (and does) fly into the air. (It might also be necessary to tell someone on the other side to do the same.)

Finally, keep in mind that some glass can be laminated. This can typically be somewhat tough to get through. Therefore, one might need to be prepared to potentially have to fight their way in or out through this type of glass. Kicking around the edge can often dislodge it from its mount, however if that doesn't work, you might have to be prepared to cut through it or look for another method of entry/exit.

All in all, Each time I've used one of these center-punch style rescue tools, I've found they work great. However, as a potential rescuer, you always want to make sure to keep the situation as safe as possible for you. That way, you can avoid becoming another person that needs medical attention or, worse yet, needs to be rescued. A good way to do this is to practice. See if you can find some car windows you can (legally) break and run through a simple scenario of what you would do if you had to get out and get in. If you can get some legitimate training, even better.