HP Color LaserJet Enterprise CM4540 MFP series - Manual (Page 109)

Paper type Tray 1 Tray 2 Optional Trays 3,
4, and 5 Automatic duplex
printing
Opaque film
1 Trays 2, 3, 4, and 5 can print on this paper in some circumstances, but HP does not guarantee results.
2 The product can automatically print on both sides for this paper type in some circumstances, but HP does not guarantee
results.
ENWW Supported paper types 89