For most drivers the best car safety hammer is a spring-loaded one: you press it against the window and an internal spring fires the tip, so it works without room to swing and without much strength. That is not just our opinion as a company that sells one. When AAA tested six escape tools, the spring-loaded tools performed better than the hammer-style tools on tempered side windows, and AAA warned that hammer-style tools are ineffective underwater. Here is what the testing shows, the one limit every buyer needs to know, and a checklist for choosing well.
What independent testing found
In 2019 AAA tested six vehicle escape tools, three spring-loaded and three hammer-style, on real vehicle side windows (AAA Newsroom):
- Four of the six tools broke tempered side windows.
- The spring-loaded tools performed better than the hammer-style tools across multiple rounds.
- None of the six broke laminated glass. The glass stayed intact even after cracking.
- AAA advised drivers not to rely on a hammer-style tool if the vehicle is submerged.
That last point matters most. The emergency people buy these tools for is the car in water, and that is exactly where swinging a hammer fails: water slows the swing, the space is tight, and the person holding it may be upside down and injured.
Spring-loaded vs manual hammer
| Spring-loaded | Manual hammer | |
|---|---|---|
| How it breaks glass | Press against the window, the spring fires a hardened tip into one small point | You swing it and the pointed head strikes the glass |
| Room needed | Almost none, it only has to touch the glass | Enough to swing |
| Strength needed | A firm press | A fast, hard swing, often more than once |
| Underwater | The spring does the work, so water resistance matters much less | AAA advises not to rely on it when submerged |
| AAA 2019 result on tempered glass | Performed better | Performed worse |
A manual hammer is better than nothing. A spring-loaded tool is better than a manual hammer, for the people most likely to need it: older drivers, children's parents in the back seat, anyone injured, anyone in water.
The limit: tempered glass only
No handheld escape tool reliably breaks laminated glass, ours included. Laminated glass has a plastic layer between two sheets, so it cracks but holds together. Windshields are laminated, and AAA found that about one in three 2018 vehicle models also had laminated side windows, although most still have at least one tempered window.
Check every side window in your car before you rely on any tool. The marking in the bottom corner of the glass often says whether it is tempered or laminated, and if it is unclear, ask the manufacturer. Our guide to tempered vs laminated car windows explains what to look for, and this article covers what to do if your side windows are laminated.
How to choose a car safety hammer: the checklist
- Spring-loaded mechanism. For the reasons above.
- A seatbelt cutter. A jammed belt is the other thing that traps people. Look for a recessed blade you can hook over the belt without exposing your fingers.
- A holder that keeps it in reach. A tool in the glove box or the door bin can be out of reach after a crash. It should mount somewhere you can reach while belted in. See where to mount a safety hammer.
- A way to practice. You should know how it feels to fire before you ever need it. AAA advises testing your tool; a practice piece lets you do that without breaking a car window.
- One per car. A tool in your car does nothing for your partner's car or your teenager's. Buy for every car the family drives.
- Skip gimmicks. Lights, chargers and extra functions do not help it break glass. The mechanism, the cutter and the holder do.
How to use one
- Unbuckle, or cut the belt if it is jammed.
- Choose a tempered side window, not the windshield.
- Press the tip firmly into a corner of the window, not the centre, until the spring fires.
- Clear the glass from the frame with the tool and get out. Children first, oldest first, then adults.
AAA's S-U-R-E steps put it simply: stay calm, unbuckle, roll down or break the window, exit quickly.
The BEAM Lab Safety Hammer
Ours is a spring-loaded tool with a tungsten tip and a stainless steel seatbelt cutter. One press fires it, with no swing needed. It comes with a holder so it stays in reach. It is made for tempered side windows, like every handheld escape tool. 30-day money-back guarantee, and family packs if you want one in every car.
Common questions
Do spring-loaded window breakers really work?
On tempered glass, yes. In AAA's 2019 testing the spring-loaded tools performed better than the hammer-style tools. No tool AAA tested broke laminated glass.
Can a safety hammer break a windshield?
No. Windshields are laminated. Use a side or rear window that is tempered.
Does a car safety hammer work underwater?
AAA advises not to rely on a hammer-style tool when submerged, because the swing is slowed by water. A spring-loaded tool fires from its own spring, so it does not depend on swing speed. Act early: it is easier to get out before the water reaches the windows.
Where should I keep it?
Mounted within reach of the driver while belted in, not in the glove box or trunk. Our mounting guide goes through the options.
How many do I need?
One per car at minimum. Larger vehicles with rear passengers benefit from a second tool within reach of the back seats.