The HD Wheel bearings are Engineered to provide Maximum Performance for the Most Demanding Applications. Designed Specifically for Mower Applications. The High Temperature Grease reduces Friction. The Result is a Cooler Operating Temperature and Extend Bearing Life. Our High Temperature Specialty Grease and World Class Quality Make The HD Switch a Best in Class Option. Maintenance is optional: All bearings are sealed with grease so they are maintenance-free, however the inner seals can be removed if you prefer scheduled maintenance.