Self-aligning filtermats are supplied with self-aligning tabs that contain holes for exact positioning fo the filtermats withing the Packard FilterMate cell harvester and other cell harvesting systems. After harvesting sample onto the filtermats and drying, the tabs are removed by cutting along the perforation lines with an Omnifilter cutting tool prior to placement into OmniFilter holders, addition of liquid scintillation cocktail, covering with TopSeal-A, and measurement on a scintillation counter.