Compatible with Roborock S50 S51 S55 robot vacuum cleaner This motor is used with a distance sensor. Exquisite and detailed, it matches the original equipment very well. Made of metal, sturdy and durable, with a long service life. The motor runs smoothly and stably, allowing the sweeper to achieve better cleaning results faster. Comes with orange pulleys for easy replacement. Size: 6*4*4 cm Note: The data are all measured manually, please allow an error of 1-3 cm due to differences in light and display, there may be some color differences, please refer to the actual item received.