This is what HP has to say: -

The HP LaserJet Pro 4002dn A4 Mono Laser Printer is designed to be used in busy environments. With a first-page print speed as fast as 6.3 seconds, you can count on it to keep up with your business needs for years to come.

Quick, quality printing

The printer has a fast print speed of up to 40 pages per minute (ppm), giving you the ability to quickly send documents out of the office at a rate that is unparalleled in the industry.

Its flexible paper handling options include a 250-sheet capacity input tray and a 100-sheet multipurpose tray. The dual-sided printing capability lets you reduce paper waste by printing on both sides of a page automatically.

The HP LaserJet Pro 4002dn has a maximum print resolution of up to 1,200 x 1,200 dpi as well as 256MB of RAM and a 1200MHz processor that makes handling large, complex documents a breeze.

Clever connectivity

It features a host of features and capabilities, including USB and Network connectivity, duplex printing and HP Wolf Pro Security. With a built-in Ethernet port, you can connect your printer to your network for shared access among multiple users.

You can also send print jobs directly from your mobile to the printer using HP Apps, AirPrint or Mopria without needing to install drivers on your device.