Canon MX720 Series Online Manual page 53

(B) Photo paper (A4, 8" x 10" (20 x 25 cm), or Letter size)
(C) Plain paper (A4, B5, A5, Letter, or Legal size)
(D) Envelopes
Loading Paper with the Print Side Facing Down
If paper has print side (front or back), such as photo paper, load it with the whiter side (or glossy side)
facing down.
(E) cassette (upper)
(F) cassette (lower)