Model and serial numbers The model number and serial number are listed on an identification label located on the back of the printer. z HP LaserJet 3100 product Model number C3948A z HP LaserJet 3150 product Model number C4256A The serial number contains information about the Country of Origin, the Revision Level, the Production Code, and production number of the HP LaserJet 3100/3150 product. The label also contains power rating and regulatory information. The label shown in Figure 1 below is a label from an HP LaserJet 3100 product. Figure 1. Model and serial number label 18 Product Information EN