Iron, about 7/8" diameter. Collected in the decades after the battle with their good form preserved and surface textured from burial. Purchased from Schindler’s Antiques, King Street, Charleston, SC in the 1980s. Grapeshot or canister shot (indistinguishable after firing) was used both on land and at sea to decimate closely grouped enemies. When used against cavalry, the greatest casualties were inflicted against the horses. These are about 40 grams. each about double the weight of a lead musket ball and impart about twice the energy upon impact. Have five.