Ah, the invention line! People always ask me to tell them which tool is best for them. It depends on where you are going and that determines what you need. We also now have mission specific packages available. 

Now back to the invention line. Each one that we invented was based on the one self defense weapon before it. We continued to make more aggressive tools, which by the way has saved many a life too. We have lots of stories of life saving!

In the spirit of active self protection, you need to understand what you really need based on where you are going. If in your house you need a more aggressive self defense tool, you might pick a D2, Owl, or Swan.