We used this with our Australian Shepard for one puppy year. As he grew older he just stayed in the house. The unit has been sitting for about 2 years unplugged. The batteries may not work but there is one in there that has never been opened. The unit itself works fine and the collar, though worn and replaceable works fine. I do not think I have have the flags that go with the unit (used for training) but they could be easily replaced with something else.PLEASE NOTE I DO NOT KNOW IF THIS IS A 300 model or 100 model. There is no model number on the actual unit but if I had to guess I would say it is the 100 although I really don’t know the difference. PLEASE SEE ACTUAL PICTURES IN THIS LISTING!!!