When the car is driving on the uneven road, there will be a speed difference between the left and right wheels. This differential is designed to effectively adjust the speed difference for 1/28 K969 K979 K989 K999 P929 P939 RC car, which is a excellent replacement part. Features: Professionally designed for 1/28 K969 K979 K989 K999 P929 P939 Car. Made of high-quality plastic material to achieve strong wear resistance and durably use. This differential could effectively adjust the speed difference between the left and right wheels when the car is driving on the uneven road. Efficiently adjusts the rotating speed difference between the inner and outer driving wheels during the turning process, thereby improving the turning ability of wheels. Compact structure, convenient assembly, enhanced design for anti-off capability. Any problem, please contact our store without hesitation. Honor to serve you. Specification: Item Name: Car Ball Differential Material: Plastic Color: Black Quantity: