A boulloterion is an iron, pliers-shaped instrument, used to impress the designs on a lead bulla seal. After the cord was wrapped around the package or document and the ends inserted in a channel in the blank seal, the seal was placed between the disc shaped engraved dies on the jaws of boulloterion. The boulloterion had a projection above the jaws, which was struck with a hammer to impress the design on the seal and close the channel around the two ends of the cord, securely locking the seal around the package or document.