Tjin, I read the following at your blog:

"- Cut the seat-belt in a 45 degree angle to minimize the chance of the webbing being bunching up and blocking the cutting action. A 90 degree cutting angles causes bunching up of the webbing."

That is an excellent point. Noted, and thanks!

A note about the LifeHammer: one of the advantages of a spring loaded device over something like the LifeHammer is that you don't have to be able to swing the Res-Q-Me. If you are injured, or the car is flooded with water, it can be very hard to swing the hammer-style tool.