Invisible(underground) dog fences-What features should I look for in a good one?

One that repels cops??

Sport Dog SDF 100

I purchased this about 3 years ago and installed it myself. Works great still. Within the first year, I believe lightning struck the loop in the yard. It was under waranty still and Sport Dog replaced it. I purchased a lighning protector for the second unit and drove a new grounding rod for it as well.

It took a full day for me to bury ~700 ft of wire. I used an walk-behind edger and went thru 2 or 3 blades.

My dog is really smart and very obedient, so training was pretty quick and she has never broken out. I followed the training suggested very closely and it worked.

Good luck

We would walk ours around the perimeter a few times early on, with the collar on, so she knew the limits. After that, we were able to remove a lot of the flags. Our dog never really tested it much. Every time we would take her past it, we would make her sit at the edge before we would tell her it was okay to cross. Works perfectly.