If you're into mechanical projects or repairs, these CNBTR bevel gears are super useful! You get 4 identical gears in this set, each with a 3mm inner hole diameter. They're 0.8 module with 15 teeth (15T), made from copper, and measure about 10mm outer diameter by 8mm height. The yellow copper material is durable and works well for various applications. Important note: these only mesh with other 0.8 module gears - you can't mix them with 0.5 module or other sizes. Each gear comes with a screw and wrench for easy installation. They're perfect for model cars, locomotives, conveying equipment, agricultural machinery, printing equipment, automotive applications - basically any situation where you need to transfer motion between shafts at an angle. The load capacity is pretty good thanks to the lower contact ratio design. They're designed for long service life with noise reduction and shock absorption features. Whether you're building something from scratch or repairing existing equipment, having these on hand is really convenient. The quality feels solid, and at this price for 4 pieces, they're a great value for hobbyists and professionals alike.