This heavy-duty compass cutter is designed to cut circles from approximately 3" to 12" diameter. Perfect for scribing circles necessary for the installation of recessed lighting, in addition to cutting cardboard, mat board, and thin plywood. This knife uses extra-sharp heavy-duty snap-off blades that allow you to simply snap-off a dull cutting edge and advance the new cutting edge. Also great for cutting half-moon wind slits in banners and cutting out small sections of carpet. Easy, tool-free blade change for convenience. Satisfaction Guaranteed.