Dogtra Boundary Kit Brand New The Dogtra Expansion Kit is a boundary kit that includes an additional 500 feet of Wire 4 Waterproof Splices and 50 Flags. It can be used to increase the size of your electric dog fence containment system and will cover approximately 1/4 acres of area. Expansion Kit Features: Boundary Kit Expands Your Containment System Covers Approximately 1/4 Acres Of Area 500Ft Spool Of Wire 50 Flags 4 Waterproof Splices