It's essentially a smoke bomb the size of your middle finger, you gently scoop out the dirt so the hole's nice & open, you light the sucker and right as it starts to go you slip it down the hole and gently cover the hole with dirt so it traps the smoke inside, burns up the oxygen in the burrow and fills the whole thing with poison smoke and fumes.

Here's some:
http://www.domyownpestcontrol.com/giant-...f691c26dd2d760c

I used one at each end of the burrow just for schits and giggles. I'm kinda hoping I'll get another mole now so I can use the other two.