Samsung SL-C1810W-XAA - Manual (Page 111)

Specifications
111 5. Appendix
a. Maximum capacity may differ depending on media weight, thickness, and environmental conditions.
b. Post card 4 x 6 is supported for tray1, Manual feeder, or Multi-purpose tray.
c. Index card (3 x 5) is supported for Manual feeder and Multi-purpose tray.
d. The smoothness of the labels used in this machine is 100 to 250 (sheffield). This means the numeric level of smoothness.