• M451nw: Supports wired (Ethernet) and wireless network connection, and Wi-Fi, but does not support automatic duplex printing (requires manual feeding). • M451dn: Supports wired (Ethernet) network connection and automatic duplex printing, but does not have built-in wireless connectivity. • M451dw: The full version that combines wireless (Wi-Fi) and automatic duplex printing together. Basic specifications for the M451 series: • Print speed: Up to 21 pages per minute (black and color). • Print resolution: 600×600 dpi with HP ImageREt 3600 color enhancement technology. • Paper trays: 50-sheet multipurpose tray, and a 250-sheet standard tray. • Cartridges used: Uses HP 305A toner cartridges (and the high-capacity black model HP LaserJet Pro 400 color wifi