If your life (or someone else's life) depends on your physical capacity, then you are a 'professional athlete'.
(This is a message I sent to a fellow gym owner who was going to go speak to a Police department and needed some ideas).
People who get paid millions of dollars to play with a ball only get paid to do that because they do it on television. They are more akin to musicians and actors. Nobody pays them to be athletic and play their sport in their backyard.
I was hired to do 3 one day seminars for a big city department on Fatigue Mitigation. I opened up with this and I had them hooked. The vast majority of them stayed awake for the 4 hours or so of the mandatory training.
(One thing I didn't have access to yet was Robb Wolf's stuff he did with the city of Reno's police. Saved them millions of dollars in health care doing some basic health intervention stuff. Could have some good info too).
Ultimately I wouldn't try and 'sell' them on your gym. I would focus more on teaching them the importance of fitness and community for their own physical and mental safety. Then at the end, make a few points as to how your gym does this.
I would focus on how you are different that what most people believe about CrossFit and not only will you be providing the physical benefits, but also some of the social ones. Cops need a place to hang out with people that know and like them. Wearing the uniform usually means you are spending your shift with people who DO NOT want to be talking to you (or downright 'hate' you at that moment). Your gym should be seen as a place to get fit and have fun with people that support and appreciate them.
(And then collect contact information to follow up with people directly! Don't give business cards, take them!)
Thrive on. (And thank you to all who wear the uniform!)
-jj