HP Deskjet 6122 Color Inkjet Printer - Manual (Page 17)

second paper tray
An optional 250-Sheet Plain Paper Tray may be included with your printer. If
it is not included, it can be purchased separately from an authorized HP
dealer.
The duplexer must be attached to the printer in order for the printer to use the 250-
Sheet Plain Paper Tray. If the duplexer is not attached to the printer, then use the In
tray for printing.
250-sheet plain paper tray description
The 250-Sheet Plain Paper Tray has two parts.
1. base 2. lower tray
The lower tray has three size adjustments.
1. paper width guide 2. paper width fence 3. paper length guide