Zildjian China Boy Low 18" China Cymbal 1350g 1981-1992 (“CO.” Stamp)Notes The CO stamps were the last unique signatures on Zildjian models until the company introduced their laser engraving system in 1994. They take their name from the CO in Zildjian CO whereas prior models read Zildjian Co. A Zildjian China Boy Low 18" China Cymbal 1350g 1981 1992 (CO. Stamp) in Excellent condition! At Evolution Music, we attempt to highlight cosmetic defects (if any) by picturing every angle of every piece of gear so you know