HP 3550 - Manual (Page 82)

3. Slide out the tray extender and, if necessary, open the additional tray extender.
4. Slide the width guides slightly wider than the print media.
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5. Place print media into the tray with the side to be printed up, and the top, short edge in
first.
NOTE If you are printing on two sides, see 2-sided (duplex) printing for loading instructions.
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70 Chapter 4 Printing tasks ENWW