This heavy-duty carpet knife with an extended stainless steel blade channel allows additional segments of blades to be extended while maintaining blade support. This feature is designed to allow for deeper cuts on thick material. For convenience, a built-in "carpet tucker" located in the rear of the handle is used to "tuck" carpet over tack strips and to secure carpeting. The ability to cut thicker materials is a distinct advantage in other cutting projects as well. Features a ratchet wheel blade lock and heavy gauge stainless steel blade channel that holds blade tight. Blades are made from high quality carbon tool steel are produced using OLFA precise multi-step production process for unparalleled sharpness and superior edge retention. Long lasting, durable snap-off blade - a new sharp edge with each snap. Easy, tool-free blade change for convenience. Guaranteed Forever.es per blade. 50 blades per pack.