Canal Zone Scott #CO8-CO12 Airpost Official Used Stamp Set. CO8 AND CO11 POSTALY USED. CO10 AND CO12 H OG. The item “Canal Zone Scott #CO8-CO12 Airpost Official Used Stamp Set” is in sale since Wednesday, October 24, 2018. This item is in the category “Stamps\United States\Possessions”. The seller is “777aaa” and is located in Riverside, California. This item can be shipped worldwide.