Greenworks 7511902 3-Piece Blade Pack for 60" OptimusZ ZTR Mower - This pack of 3 blades is for use with the Greenworks 60" OptimusZ ZTR Mower. Made for easy installation and use, these blades will help ensure the best service life possible. The OptimusZ ZTR Mower is an ultra-high-performance mower that operates with the equivalent power of a 65HP and 1040cc displacement gas engine. With a constant 19,000FPM blade tip speed, the mower skillfully adjusts to various grass conditions to ensure the best cut quality.