If you are printing on mailing labels that are 1 x 3 inches, the Lines Per Form must be 6. However, you will only be able to print on 5 of those 6 lines.

If you are printing on mailing labels that are 1.5 x 4 inches, the Lines Per Form must be 9 (i.e., 6 x 1.5). However, you will only be able to print on 8 of those 9 lines.

If you are printing on a rotary index card that is 2 x 4 inches, the Lines Per Form must be 12 (i.e., 6 x 2).