Flat plastic circle, with the exact 50 cm (20") inside diameter.
Circles are NOT a required item.
They only started using them in France around 2007 for official competitions.
Can NOT ship by Flat Rate Priority Mail. Given the size of the carton (24"x24"x4"), shipping cost calculated may come out expensive. We'll do our best to reduce it when possible, before debiting you card or Paypal. It also depends if / what else you order that can fit in that same carton. Adding weight (boules) will make it more economical overall.