This heavy-duty compass cutter 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 wind slits in banners and cutting out small sections of carpet. To make half-moon wind vents in banners, simply cut 4" to 8" diameter 1/2 moon wind slits in the center of the banner. Features an Easy, tool-free blade change for convenience. Guaranteed Forever.