High-quality material: The universal connection nut is made of high-quality alloy steel material, which is strong and durable. CNC mechanical design: 4mm motor coupler has a special design, perfect workmanship, precise size, convenient and quick installation and disassembly. 360-degree rotatable universal joint: This mm joint count can change the transmission direction at any point, which is very flexible and easy to use. Application: 4 mm rotation coupling is perfect for remote control model and remote control model boats, as well as perfect motor shaft assembly accessories. Material:alloy steel colour:Silver Package Contents: 4 x Cardan Coupling Connector 8 x screws 2 x Wrench Only the above package content, other products are not included. Note: Light and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.