The 4V relates to the frequency of triangles in the structure. The higher the "V" is the stronger and rounder your dome will turn out. We carry 4V greenhouse dome kits, PVC chicken coop domes, geodesic event domes, dome shelters for Burning Man, outdoor shelter domes, and any other Geodesic Shelter you can dream up. We carry both hub only kits and full kits that include the pre-cut and color coded PVC struts. Easy to follow dome build instructions.