1.Compatibility: This lawnmower blade disc is specifically designed to fit various models of the series, for 420 (2016 - 2017), for 430X (2016 - 2017), for 430X (new) (2018) , for 440 (2017), for 450X (2016 - 2017, 2018), for 520 (2018), for 550 (2018),a perfect match for optimal performance. 2.Cutting: Engineered for sharpness and durability, the blade disc provides efficient cutting capabilities, helping to maintain a pristine lawn with every use. 3.Easy Installation: The user-friendly design allows for straightforward installation, enabling you to quickly replace the blade disc without any tools or technical skills. 4.Materials: Constructed from high-grade materials, this blade disc is built to withstand the rigors of outdoor use, offering long-lasting reliability and performance. 5.Enhanced Lawn Health: By providing a clean and even cut, this blade disc promotes healthier grass growth, enhancing the overall appearance and vitality of your lawn. Color: Black Material: Plastic+Metal Package Contents: 1 x Cutterhead Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.