Is it Special Wire?
What kind of wire is used for the boundary? Is it special wire? Can I get the wire from the hardware store? Do I need to get the wire from you?
You can use pretty much any insulated single core wire. It does not matter if the wire is solid core, or has a stranded core. Try and find a wire that is “rated for direct burial.” This wire tends to last longer in the ground than regular PVC coated wire that can break down over time, particularly where there are acidic soils. You can find this type of wire in most hardware stores and most electrical supply stores. It is typically used for sprinkler systems and outdoor lighting.