Unlike the Wasp WPL label printers, the WHC25 is designed to stop at the black mark in the middle of the wristband media, rather than feeding out to the perforation. This will leave a few inches of the striped unprintable area protruding from the front of the printer after the printed wristband is ripped off, and the printer will be aligned to begin the next print job.

The label should be designed with a layout set to 1.25" width, 3.0" height, and a top page margin of 0.8". This will position the print out properly in the white area of the wristband media, and after printing, the printer will advance to the next black mark before beginning the next print.

https://dl.waspbarcode.com/wasp/supportfiles/kbimages/Printers/WHC25Printing.zip includes my label file and a video showing how it prints.