There are several containment systems on the market, not all are made the same even with-in one brand. SportDOG has an upgraded wire 14 or 16 gauge wire.  In Minnesota and several other states winter can be an issue with the ground freezing and thawing. Depending on your area needed below sizes go as shown below. If you don't have a fenced in yard this is the next choice to keep your dog safe. Let me know if you are looking for a differnet lenth.