if you would, chris, give us a sense, tell us about rock. >> so rock is a german shepard that we got from the fort worth shelter. we were looking for a dog that had high energy, and we wanted to see if we could find a rescue. rock just turned out to be the perfect dog we were looking f high energy and great drive. really glad to come across him. nicole: i absolutely love a good rescue story. tell us how dogs are able to work and potentially find more pills than, say is, a human could. >> this is the tool, it's actually the only tool that we have that can go beyond our own eyesight. as an investigator, you're limited. these guys have a superpower, and it's their nose, and that that allows us to get into areas we simply can't get into without them. so they're critical. will: so i have two questions, i hope you'll both forgive me. what can he do? fentanyl? how many different things can he sniff out?