This is a 5mm pitch, 16-tooth timing belt pulley (sprocket/gear wheel) made for use with 15mm or 20mm wide timing belts. The center bore is un-drilled, so you can drill it out to fit your shaft size between 5mm and 12mm. It's an unbranded, generic pulley made in China, perfect for 3D printers, CNC machines, robotics, or any small mechanical project that uses synchronous belts. Brand new and ready for your custom machining. A versatile and affordable component for makers and engineers. No MPN.