Talking to this new generation of crime fighters, I often have to stop and explain how the world was "then" compared to how the world is "now." When I started with Tucson PD more than 40 years ago, we didn't have portable radios, computers in our cars, TASERs, OC spray, dash cams, or Glocks. If you needed to talk to a dispatcher by phone you went to something called a "phone booth" and gave them a number out of your "notebook," which was a spiral bound pad of lined paper.

Your phone was on the end of a thing called a "cord" and if someone wanted to send you a message he or she either wrote a memo and sent it in something called an envelope, or wrote a note by hand and put it in your little wooden mailbox, which was on a wall in the station with your badge number on it. You had six rounds in your "revolver" and 12 more in your speed loader, and you only shot at seven, 15, 25, and finally 50 yards, prone and single-action.

One day in the spring of 1975 a group of us were at the range qualifying when someone discovered a catalog for a new company called "Second Chance." It told the story of this somewhat eccentric former Marine who had been shot delivering pizza. The guy didn't die but he was badly hurt, and he wondered why there was no reliable, wearable protection against bullets. Doctors said even if you stopped the bullet on the outside energy would be transmitted into your internal organs, killing you anyway. "Blunt trauma" was deadly, he was told; but then why didn't he die when he was actually shot and suffered real penetrating trauma?

So this fellow invented soft body armor, and he routinely shot himself in the chest to prove it worked. The catalog was full of stories of officers and deputies already being saved by his new creation; he called them "saves." We were sold! I put a group order together and called the number in the catalog and had my first conversation with the father of modern body armor, Rich Davis. He was so excited about his new invention that he not only gave us a good deal, he sent us a bunch of test swatches to experiment with to see how effective this new armor was.

We shot it with .38s, .44s, .357s, and finally a buddy's 9mm. That shut us up because the cheapo military surplus 9 punched right through. Damn, that was a tough one to stop. Fortunately, in those days, the most common round shot at law enforcement was the .22 and it was stopped easily by our new vests. Don't get me wrong, the .22 is still very dangerous, but in the 1970s it was the round that killed the most police officers year in and year out. The key to saving lives was getting these new vests widely distributed throughout our profession.

Today it seems obvious that everyone should have jumped on the armor bandwagon back then, but I had many a veteran tell me wearing armor would just make us reckless, or bad guys would just shoot for our heads anyway, or blunt trauma would damage our hearts even if the bullets were stopped. But slowly and surely body armor became as standard as our handguns. Innovation after innovation has made the armor more and more comfortable, concealable, and effective, and today we have a wonderful assortment of models for any assignment.

Next to training and modern medicine, the single most important factor in the increased survivability of today's police officer is this modern version of the chainmail worn into combat for centuries by warriors. Back then no clear-thinking fighter would have been caught dead without his mail under his tunic, so what is our excuse?

Every year too many of our modern warriors die without anything but skin under their tunics. Today's bad guy doesn't have a .22 anymore. In fact, the most common round used to kill our brothers and sisters is that nasty little 9mm. We mock it as a low stopping power round, but any coroner will attest to its lethality; never confuse stopping power with lethality.

So, my young crime fighters of today, while you laugh at us old timers for not having had cellphones or laptops or "autos," all of which you couldn't live without, remember to wear the one thing that you can surely live with: your wonderful modern body armor.

Dave Smith is an internationally recognized law enforcement trainer and is the creator of "JD Buck Savage." You can follow Buck on Twitter at @thebucksavage.