Features: Accurate transmission without slipping at work, having a constant gear ratio. Smooth transmission, strong capacity of buffer and damping, low noise; higher transmission efficiency, better energy-saving effect. Stable operation and easy maintenance , no need of lubricants. Package comes with 5pcs 20 teeth GT2 timing pulley (bore diameter 5mm), 5 meters GT2 timing Belt and 1 hexagon wrench. High-quality components guarantee the efficient operation of the 3D printer.