Quiet operate under 30dB noise perfect for libraries and offices while maintaining in construction and maintenance engineered bearings ensures smooth rolling with 25% less friction, enhancing efficiency in workshops and factory operations Special anticorrosion protects against rust, making these pulleys suitable for outdoor and harsh environment use Heavy duty metal construction with bearing steel provide durability and a most load capacity of 67kg, ideal for industrial applications and heavy machinery use Versatile trapezoidal grooves design fit multiple devices, compatible for 3mm to 10mm pulley systems for projects and engineering tasks, Manufacturer: Whoasyst