Just realized that I talked about DPI, but didn't post a link. Here you go:
http://www.bulletproofvestusa.com/
On a side note, I did a ride-along with Las Vegas Metro on Friday and wore my vest. I have to say it didn't bother me a bit. I decided on wearing one UnderArmor heatgear tight fitting shirt against my body, then the vest over that, then another UA heatgear tight shirt, one size smaller, over the vest to keep it in place. Then a regular long sleeve polo over that. Very comfortable for the day.