PetSafe PIF00-12917 Stay and Play Wireless Fence

I have 3 Belgian Malinois, a Black Lab, and a new yard without a fence. I did a lot of research and ordered the Stay and Play and then ordered 3 extra collars. The unit is pretty compact and neat looking and is about the size and shape of a blender without the pitcher on it. I plugged in the unit and was pleasantly surprised to see that all of the collars worked with the unit without doing anything to them at all. I thought I would have to sync them like you would garage door opener.

http://www.lowcosttoday.com/petsafe-pif00-12917-stay-and-play-wireless-fence/