HP LaserJet 5P Printer Service Supplement Product Information Model and Serial Numbers The model number and serial numbers are listed on identification labels located on the rear of the printer. The model number is alphanumeric, such as C3150A for the HP LaserJet 5P printer and C3155A for the HP LaserJet 5MP printer. The serial number contains information about the Country of Origin, the Revision Level, the Production Code, and production number of the printer. The rear labels also contain power rating and regulatory information as shown in Figure 3. Figure 3 Sample Model and Serial Number Labels 5