They were not used to seal an object but rather as a kind of voucher or token. See Nahman Avigad, “Two Hebrew ‘Fiscal’ Bullae,” Israel Exploration Journal 40 (1990), pp. 262–266; Robert Deutsch, “Six Hebrew Fiscal Bullae from the Time of Hezekiah,” in Meir Lubetski and Edith Lubetski, eds., New Inscriptions and Seals Relating to the Biblical World (Atlanta: Society of Biblical Literature, 2012), pp. 59–67; Gabriel Barkay, “Evidence of the Taxation System of the Judean Kingdom—A Fiscal Bulla from the Slopes of the Temple Mount and the Phenomenon of Fiscal Bullae,” in Meir Lubetski and Edith Lubetski, eds., Recording New Epigraphic Evidence: Essays in Honor of Robert Deutsch (Jerusalem: Leshon Limudim Ltd., 2015), pp. 17–50.