When printing via your Android or iOS device, Rollo Wireless Printer can recognize and automatically crop your labels into 4"x6" size. 

How do you know if your label needs to be cropped? You'd notice that it's on a larger paper with a lot of space/borders around and the 4"x6" label that you need to print is only a small part of the print preview as shown in the example below:

When you have this kind of label, simply proceed and print it and Rollo will automatically crop it to 4 x 6 size

If you are printing from a Desktop Computer, you will need to crop the label before sending it to Rollo. Please refer to this article: Cropping a full size 8.5" x 11" page to a 4" x 6" label Print