I have one for my black lab. It's currently inoperable due to the utility company cutting the underground wire in the middle of the yard somewhere.

Anyhow... They are great!!!!!!! It takes a little while to teach the dog where his boundries are, but once they are trained, they DO NOT cross the line.

Basically what you do is
-Lay wire
-Set up flags at the edge of the radio feild
-[on leash] Train dog w/ shock collar (Rubber dummy prongs to prevent shock) to run back in yard once he hears the warning beeps. Offer LOTS of praise.
-[on leash] Put regular prongs on collar. Take dog to edge of flags. Collar will start beeping. Let dog get shocked. Offer LOTS of praise.
-[on leash] Work dog around paremiter until he reailizes that beep = = shock. LOTS of praise for going back into the "safe zone". Remove half of the flags (every other one) after one week of training in this stage. Remove half of the ones left a week after, then remove all flags in 3rd week. This can coincide with the next step as well.
-[off leash] Let dog wonder by himself, if he gets near field, he will get shocked. Should run back into yard.

Please note that this takes a couple weeks to complete. but once finished, you really shouldn't need to turn on the fence unless your pup needs a constant reminder.

If you want more technical instructions, let me know.

BTW, Nitro's (my lab) fence hasn't worked for over 6 months and he hasn't even thought of crossing that parimeter. Much cheaper solution than a chainlink fence. Try $300 for 1+ acres compared to $5000 1/4 acre of chainlink.