HP LaserJet Pro M521 Multifunction Printer series - Manual (Page 35)

Load Tray 2 and optional Tray 3
NOTE: The procedure to load paper for Tray 3 is the same as for Tray 2. Only Tray 2 is shown here.
1. Pull the tray out and lift up slightly to remove it
completely from the product.
2. Pinch the release that is located on the left
guide and slide the side guides to the correct
paper size.
3. Pinch the release that is located on the rear
paper guide and slide it to the correct paper
size.
ENWW Tray 2 and optional Tray 3 21