efficiency power transmission, ideal for 3D printers and other precision belt or shaft drive applications. Improves drive smoothness and overall system performance. Hole diameters (bore options): 14 mm, 16 mm, 18 mm, 19 mm, 22 mm, 24 mm, 25 mm, 28 mm. Material and build: made of aluminum alloy with fine workmanship, smooth surface, and sturdy, durable construction. Surface treatment: has a oxidation finished surface for anticorrosion and antirust protection, contributing to long service life. Broad compatibility: widely used in 3D printers, CNC machines, stepping motors, and other precision transmission equipment. Use cases: 1) Upgrading a 3D printer drive system to improve power transmission efficiency and reduce drive slippage. 2) Replacing worn or degraded components in small CNC machines or router setups to restore precise motion transfer. 3) Integrating into beltdriven or shaftdriven automation projects, including robotics and hobbyist builds, where multiple bore sizes are needed to match motors and pulleys.