OEM Scag Mower Blades for the Z-Cat Zero-Turn. Cutter blades are the most important element in maintaining top quality cutting quality. Blades must be kept sharp so grass is cut off cleanly. Dull blades leave a poor quality of cut and damages the grass by tearing and bruising the grass rather than cutting it. In addition, dull blades slow cutting speed, waste power and fuel, and put unnecessary strain