Miners usually had two checks with the same number on them. One, frequently made of aluminium, would be left with the banksman so that he knew how many men were underground and who they were. The second check which was usually made from brass would be kept by the miner and taken underground. When the miner came out of the mine after his shift he would give the brass check to the banksman who would match it back up with the aluminium check. Both checks would be returned to the lamp room ready for collection the next day. There are systems which involved three or more checks but the two check system was the most common. Checks were replaced in later times by a plastic swipe card system.
